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<!DOCTYPE html><meta charset="UTF-8"><meta http-equiv="Content-Language" content="en" /><title>functions.js</title><link href="../../../../dossier.css" rel="stylesheet" type="text/css"><div id="main-wrapper"><input type="checkbox" id="sidenav-toggle" /><main><header><h1>lib/goog/functions/functions.js</h1></header><pre><table class="srcfile"><tbody><tr><td><a name="l1" href="#l1">1</a><td>// Copyright 2008 The Closure Library Authors. All Rights Reserved.<tr><td><a name="l2" href="#l2">2</a><td>//<tr><td><a name="l3" href="#l3">3</a><td>// Licensed under the Apache License, Version 2.0 (the &quot;License&quot;);<tr><td><a name="l4" href="#l4">4</a><td>// you may not use this file except in compliance with the License.<tr><td><a name="l5" href="#l5">5</a><td>// You may obtain a copy of the License at<tr><td><a name="l6" href="#l6">6</a><td>//<tr><td><a name="l7" href="#l7">7</a><td>// http://www.apache.org/licenses/LICENSE-2.0<tr><td><a name="l8" href="#l8">8</a><td>//<tr><td><a name="l9" href="#l9">9</a><td>// Unless required by applicable law or agreed to in writing, software<tr><td><a name="l10" href="#l10">10</a><td>// distributed under the License is distributed on an &quot;AS-IS&quot; BASIS,<tr><td><a name="l11" href="#l11">11</a><td>// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<tr><td><a name="l12" href="#l12">12</a><td>// See the License for the specific language governing permissions and<tr><td><a name="l13" href="#l13">13</a><td>// limitations under the License.<tr><td><a name="l14" href="#l14">14</a><td><tr><td><a name="l15" href="#l15">15</a><td>/**<tr><td><a name="l16" href="#l16">16</a><td> * @fileoverview Utilities for creating functions. Loosely inspired by the<tr><td><a name="l17" href="#l17">17</a><td> * java classes: http://goo.gl/GM0Hmu and http://goo.gl/6k7nI8.<tr><td><a name="l18" href="#l18">18</a><td> *<tr><td><a name="l19" href="#l19">19</a><td> * @author nicksantos@google.com (Nick Santos)<tr><td><a name="l20" href="#l20">20</a><td> */<tr><td><a name="l21" href="#l21">21</a><td><tr><td><a name="l22" href="#l22">22</a><td><tr><td><a name="l23" href="#l23">23</a><td>goog.provide(&#39;goog.functions&#39;);<tr><td><a name="l24" href="#l24">24</a><td><tr><td><a name="l25" href="#l25">25</a><td><tr><td><a name="l26" href="#l26">26</a><td>/**<tr><td><a name="l27" href="#l27">27</a><td> * Creates a function that always returns the same value.<tr><td><a name="l28" href="#l28">28</a><td> * @param {T} retValue The value to return.<tr><td><a name="l29" href="#l29">29</a><td> * @return {function():T} The new function.<tr><td><a name="l30" href="#l30">30</a><td> * @template T<tr><td><a name="l31" href="#l31">31</a><td> */<tr><td><a name="l32" href="#l32">32</a><td>goog.functions.constant = function(retValue) {<tr><td><a name="l33" href="#l33">33</a><td> return function() {<tr><td><a name="l34" href="#l34">34</a><td> return retValue;<tr><td><a name="l35" href="#l35">35</a><td> };<tr><td><a name="l36" href="#l36">36</a><td>};<tr><td><a name="l37" href="#l37">37</a><td><tr><td><a name="l38" href="#l38">38</a><td><tr><td><a name="l39" href="#l39">39</a><td>/**<tr><td><a name="l40" href="#l40">40</a><td> * Always returns false.<tr><td><a name="l41" href="#l41">41</a><td> * @type {function(...): boolean}<tr><td><a name="l42" href="#l42">42</a><td> */<tr><td><a name="l43" href="#l43">43</a><td>goog.functions.FALSE = goog.functions.constant(false);<tr><td><a name="l44" href="#l44">44</a><td><tr><td><a name="l45" href="#l45">45</a><td><tr><td><a name="l46" href="#l46">46</a><td>/**<tr><td><a name="l47" href="#l47">47</a><td> * Always returns true.<tr><td><a name="l48" href="#l48">48</a><td> * @type {function(...): boolean}<tr><td><a name="l49" href="#l49">49</a><td> */<tr><td><a name="l50" href="#l50">50</a><td>goog.functions.TRUE = goog.functions.constant(true);<tr><td><a name="l51" href="#l51">51</a><td><tr><td><a name="l52" href="#l52">52</a><td><tr><td><a name="l53" href="#l53">53</a><td>/**<tr><td><a name="l54" href="#l54">54</a><td> * Always returns NULL.<tr><td><a name="l55" href="#l55">55</a><td> * @type {function(...): null}<tr><td><a name="l56" href="#l56">56</a><td> */<tr><td><a name="l57" href="#l57">57</a><td>goog.functions.NULL = goog.functions.constant(null);<tr><td><a name="l58" href="#l58">58</a><td><tr><td><a name="l59" href="#l59">59</a><td><tr><td><a name="l60" href="#l60">60</a><td>/**<tr><td><a name="l61" href="#l61">61</a><td> * A simple function that returns the first argument of whatever is passed<tr><td><a name="l62" href="#l62">62</a><td> * into it.<tr><td><a name="l63" href="#l63">63</a><td> * @param {T=} opt_returnValue The single value that will be returned.<tr><td><a name="l64" href="#l64">64</a><td> * @param {...*} var_args Optional trailing arguments. These are ignored.<tr><td><a name="l65" href="#l65">65</a><td> * @return {T} The first argument passed in, or undefined if nothing was passed.<tr><td><a name="l66" href="#l66">66</a><td> * @template T<tr><td><a name="l67" href="#l67">67</a><td> */<tr><td><a name="l68" href="#l68">68</a><td>goog.functions.identity = function(opt_returnValue, var_args) {<tr><td><a name="l69" href="#l69">69</a><td> return opt_returnValue;<tr><td><a name="l70" href="#l70">70</a><td>};<tr><td><a name="l71" href="#l71">71</a><td><tr><td><a name="l72" href="#l72">72</a><td><tr><td><a name="l73" href="#l73">73</a><td>/**<tr><td><a name="l74" href="#l74">74</a><td> * Creates a function that always throws an error with the given message.<tr><td><a name="l75" href="#l75">75</a><td> * @param {string} message The error message.<tr><td><a name="l76" href="#l76">76</a><td> * @return {!Function} The error-throwing function.<tr><td><a name="l77" href="#l77">77</a><td> */<tr><td><a name="l78" href="#l78">78</a><td>goog.functions.error = function(message) {<tr><td><a name="l79" href="#l79">79</a><td> return function() {<tr><td><a name="l80" href="#l80">80</a><td> throw Error(message);<tr><td><a name="l81" href="#l81">81</a><td> };<tr><td><a name="l82" href="#l82">82</a><td>};<tr><td><a name="l83" href="#l83">83</a><td><tr><td><a name="l84" href="#l84">84</a><td><tr><td><a name="l85" href="#l85">85</a><td>/**<tr><td><a name="l86" href="#l86">86</a><td> * Creates a function that throws the given object.<tr><td><a name="l87" href="#l87">87</a><td> * @param {*} err An object to be thrown.<tr><td><a name="l88" href="#l88">88</a><td> * @return {!Function} The error-throwing function.<tr><td><a name="l89" href="#l89">89</a><td> */<tr><td><a name="l90" href="#l90">90</a><td>goog.functions.fail = function(err) {<tr><td><a name="l91" href="#l91">91</a><td> return function() {<tr><td><a name="l92" href="#l92">92</a><td> throw err;<tr><td><a name="l93" href="#l93">93</a><td> }<tr><td><a name="l94" href="#l94">94</a><td>};<tr><td><a name="l95" href="#l95">95</a><td><tr><td><a name="l96" href="#l96">96</a><td><tr><td><a name="l97" href="#l97">97</a><td>/**<tr><td><a name="l98" href="#l98">98</a><td> * Given a function, create a function that keeps opt_numArgs arguments and<tr><td><a name="l99" href="#l99">99</a><td> * silently discards all additional arguments.<tr><td><a name="l100" href="#l100">100</a><td> * @param {Function} f The original function.<tr><td><a name="l101" href="#l101">101</a><td> * @param {number=} opt_numArgs The number of arguments to keep. Defaults to 0.<tr><td><a name="l102" href="#l102">102</a><td> * @return {!Function} A version of f that only keeps the first opt_numArgs<tr><td><a name="l103" href="#l103">103</a><td> * arguments.<tr><td><a name="l104" href="#l104">104</a><td> */<tr><td><a name="l105" href="#l105">105</a><td>goog.functions.lock = function(f, opt_numArgs) {<tr><td><a name="l106" href="#l106">106</a><td> opt_numArgs = opt_numArgs || 0;<tr><td><a name="l107" href="#l107">107</a><td> return function() {<tr><td><a name="l108" href="#l108">108</a><td> return f.apply(this, Array.prototype.slice.call(arguments, 0, opt_numArgs));<tr><td><a name="l109" href="#l109">109</a><td> };<tr><td><a name="l110" href="#l110">110</a><td>};<tr><td><a name="l111" href="#l111">111</a><td><tr><td><a name="l112" href="#l112">112</a><td><tr><td><a name="l113" href="#l113">113</a><td>/**<tr><td><a name="l114" href="#l114">114</a><td> * Creates a function that returns its nth argument.<tr><td><a name="l115" href="#l115">115</a><td> * @param {number} n The position of the return argument.<tr><td><a name="l116" href="#l116">116</a><td> * @return {!Function} A new function.<tr><td><a name="l117" href="#l117">117</a><td> */<tr><td><a name="l118" href="#l118">118</a><td>goog.functions.nth = function(n) {<tr><td><a name="l119" href="#l119">119</a><td> return function() {<tr><td><a name="l120" href="#l120">120</a><td> return arguments[n];<tr><td><a name="l121" href="#l121">121</a><td> };<tr><td><a name="l122" href="#l122">122</a><td>};<tr><td><a name="l123" href="#l123">123</a><td><tr><td><a name="l124" href="#l124">124</a><td><tr><td><a name="l125" href="#l125">125</a><td>/**<tr><td><a name="l126" href="#l126">126</a><td> * Given a function, create a new function that swallows its return value<tr><td><a name="l127" href="#l127">127</a><td> * and replaces it with a new one.<tr><td><a name="l128" href="#l128">128</a><td> * @param {Function} f A function.<tr><td><a name="l129" href="#l129">129</a><td> * @param {T} retValue A new return value.<tr><td><a name="l130" href="#l130">130</a><td> * @return {function(...[?]):T} A new function.<tr><td><a name="l131" href="#l131">131</a><td> * @template T<tr><td><a name="l132" href="#l132">132</a><td> */<tr><td><a name="l133" href="#l133">133</a><td>goog.functions.withReturnValue = function(f, retValue) {<tr><td><a name="l134" href="#l134">134</a><td> return goog.functions.sequence(f, goog.functions.constant(retValue));<tr><td><a name="l135" href="#l135">135</a><td>};<tr><td><a name="l136" href="#l136">136</a><td><tr><td><a name="l137" href="#l137">137</a><td><tr><td><a name="l138" href="#l138">138</a><td>/**<tr><td><a name="l139" href="#l139">139</a><td> * Creates the composition of the functions passed in.<tr><td><a name="l140" href="#l140">140</a><td> * For example, (goog.functions.compose(f, g))(a) is equivalent to f(g(a)).<tr><td><a name="l141" href="#l141">141</a><td> * @param {function(...[?]):T} fn The final function.<tr><td><a name="l142" href="#l142">142</a><td> * @param {...Function} var_args A list of functions.<tr><td><a name="l143" href="#l143">143</a><td> * @return {function(...[?]):T} The composition of all inputs.<tr><td><a name="l144" href="#l144">144</a><td> * @template T<tr><td><a name="l145" href="#l145">145</a><td> */<tr><td><a name="l146" href="#l146">146</a><td>goog.functions.compose = function(fn, var_args) {<tr><td><a name="l147" href="#l147">147</a><td> var functions = arguments;<tr><td><a name="l148" href="#l148">148</a><td> var length = functions.length;<tr><td><a name="l149" href="#l149">149</a><td> return function() {<tr><td><a name="l150" href="#l150">150</a><td> var result;<tr><td><a name="l151" href="#l151">151</a><td> if (length) {<tr><td><a name="l152" href="#l152">152</a><td> result = functions[length - 1].apply(this, arguments);<tr><td><a name="l153" href="#l153">153</a><td> }<tr><td><a name="l154" href="#l154">154</a><td><tr><td><a name="l155" href="#l155">155</a><td> for (var i = length - 2; i &gt;= 0; i--) {<tr><td><a name="l156" href="#l156">156</a><td> result = functions[i].call(this, result);<tr><td><a name="l157" href="#l157">157</a><td> }<tr><td><a name="l158" href="#l158">158</a><td> return result;<tr><td><a name="l159" href="#l159">159</a><td> };<tr><td><a name="l160" href="#l160">160</a><td>};<tr><td><a name="l161" href="#l161">161</a><td><tr><td><a name="l162" href="#l162">162</a><td><tr><td><a name="l163" href="#l163">163</a><td>/**<tr><td><a name="l164" href="#l164">164</a><td> * Creates a function that calls the functions passed in in sequence, and<tr><td><a name="l165" href="#l165">165</a><td> * returns the value of the last function. For example,<tr><td><a name="l166" href="#l166">166</a><td> * (goog.functions.sequence(f, g))(x) is equivalent to f(x),g(x).<tr><td><a name="l167" href="#l167">167</a><td> * @param {...Function} var_args A list of functions.<tr><td><a name="l168" href="#l168">168</a><td> * @return {!Function} A function that calls all inputs in sequence.<tr><td><a name="l169" href="#l169">169</a><td> */<tr><td><a name="l170" href="#l170">170</a><td>goog.functions.sequence = function(var_args) {<tr><td><a name="l171" href="#l171">171</a><td> var functions = arguments;<tr><td><a name="l172" href="#l172">172</a><td> var length = functions.length;<tr><td><a name="l173" href="#l173">173</a><td> return function() {<tr><td><a name="l174" href="#l174">174</a><td> var result;<tr><td><a name="l175" href="#l175">175</a><td> for (var i = 0; i &lt; length; i++) {<tr><td><a name="l176" href="#l176">176</a><td> result = functions[i].apply(this, arguments);<tr><td><a name="l177" href="#l177">177</a><td> }<tr><td><a name="l178" href="#l178">178</a><td> return result;<tr><td><a name="l179" href="#l179">179</a><td> };<tr><td><a name="l180" href="#l180">180</a><td>};<tr><td><a name="l181" href="#l181">181</a><td><tr><td><a name="l182" href="#l182">182</a><td><tr><td><a name="l183" href="#l183">183</a><td>/**<tr><td><a name="l184" href="#l184">184</a><td> * Creates a function that returns true if each of its components evaluates<tr><td><a name="l185" href="#l185">185</a><td> * to true. The components are evaluated in order, and the evaluation will be<tr><td><a name="l186" href="#l186">186</a><td> * short-circuited as soon as a function returns false.<tr><td><a name="l187" href="#l187">187</a><td> * For example, (goog.functions.and(f, g))(x) is equivalent to f(x) &amp;&amp; g(x).<tr><td><a name="l188" href="#l188">188</a><td> * @param {...Function} var_args A list of functions.<tr><td><a name="l189" href="#l189">189</a><td> * @return {function(...[?]):boolean} A function that ANDs its component<tr><td><a name="l190" href="#l190">190</a><td> * functions.<tr><td><a name="l191" href="#l191">191</a><td> */<tr><td><a name="l192" href="#l192">192</a><td>goog.functions.and = function(var_args) {<tr><td><a name="l193" href="#l193">193</a><td> var functions = arguments;<tr><td><a name="l194" href="#l194">194</a><td> var length = functions.length;<tr><td><a name="l195" href="#l195">195</a><td> return function() {<tr><td><a name="l196" href="#l196">196</a><td> for (var i = 0; i &lt; length; i++) {<tr><td><a name="l197" href="#l197">197</a><td> if (!functions[i].apply(this, arguments)) {<tr><td><a name="l198" href="#l198">198</a><td> return false;<tr><td><a name="l199" href="#l199">199</a><td> }<tr><td><a name="l200" href="#l200">200</a><td> }<tr><td><a name="l201" href="#l201">201</a><td> return true;<tr><td><a name="l202" href="#l202">202</a><td> };<tr><td><a name="l203" href="#l203">203</a><td>};<tr><td><a name="l204" href="#l204">204</a><td><tr><td><a name="l205" href="#l205">205</a><td><tr><td><a name="l206" href="#l206">206</a><td>/**<tr><td><a name="l207" href="#l207">207</a><td> * Creates a function that returns true if any of its components evaluates<tr><td><a name="l208" href="#l208">208</a><td> * to true. The components are evaluated in order, and the evaluation will be<tr><td><a name="l209" href="#l209">209</a><td> * short-circuited as soon as a function returns true.<tr><td><a name="l210" href="#l210">210</a><td> * For example, (goog.functions.or(f, g))(x) is equivalent to f(x) || g(x).<tr><td><a name="l211" href="#l211">211</a><td> * @param {...Function} var_args A list of functions.<tr><td><a name="l212" href="#l212">212</a><td> * @return {function(...[?]):boolean} A function that ORs its component<tr><td><a name="l213" href="#l213">213</a><td> * functions.<tr><td><a name="l214" href="#l214">214</a><td> */<tr><td><a name="l215" href="#l215">215</a><td>goog.functions.or = function(var_args) {<tr><td><a name="l216" href="#l216">216</a><td> var functions = arguments;<tr><td><a name="l217" href="#l217">217</a><td> var length = functions.length;<tr><td><a name="l218" href="#l218">218</a><td> return function() {<tr><td><a name="l219" href="#l219">219</a><td> for (var i = 0; i &lt; length; i++) {<tr><td><a name="l220" href="#l220">220</a><td> if (functions[i].apply(this, arguments)) {<tr><td><a name="l221" href="#l221">221</a><td> return true;<tr><td><a name="l222" href="#l222">222</a><td> }<tr><td><a name="l223" href="#l223">223</a><td> }<tr><td><a name="l224" href="#l224">224</a><td> return false;<tr><td><a name="l225" href="#l225">225</a><td> };<tr><td><a name="l226" href="#l226">226</a><td>};<tr><td><a name="l227" href="#l227">227</a><td><tr><td><a name="l228" href="#l228">228</a><td><tr><td><a name="l229" href="#l229">229</a><td>/**<tr><td><a name="l230" href="#l230">230</a><td> * Creates a function that returns the Boolean opposite of a provided function.<tr><td><a name="l231" href="#l231">231</a><td> * For example, (goog.functions.not(f))(x) is equivalent to !f(x).<tr><td><a name="l232" href="#l232">232</a><td> * @param {!Function} f The original function.<tr><td><a name="l233" href="#l233">233</a><td> * @return {function(...[?]):boolean} A function that delegates to f and returns<tr><td><a name="l234" href="#l234">234</a><td> * opposite.<tr><td><a name="l235" href="#l235">235</a><td> */<tr><td><a name="l236" href="#l236">236</a><td>goog.functions.not = function(f) {<tr><td><a name="l237" href="#l237">237</a><td> return function() {<tr><td><a name="l238" href="#l238">238</a><td> return !f.apply(this, arguments);<tr><td><a name="l239" href="#l239">239</a><td> };<tr><td><a name="l240" href="#l240">240</a><td>};<tr><td><a name="l241" href="#l241">241</a><td><tr><td><a name="l242" href="#l242">242</a><td><tr><td><a name="l243" href="#l243">243</a><td>/**<tr><td><a name="l244" href="#l244">244</a><td> * Generic factory function to construct an object given the constructor<tr><td><a name="l245" href="#l245">245</a><td> * and the arguments. Intended to be bound to create object factories.<tr><td><a name="l246" href="#l246">246</a><td> *<tr><td><a name="l247" href="#l247">247</a><td> * Callers should cast the result to the appropriate type for proper type<tr><td><a name="l248" href="#l248">248</a><td> * checking by the compiler.<tr><td><a name="l249" href="#l249">249</a><td> * @param {!Function} constructor The constructor for the Object.<tr><td><a name="l250" href="#l250">250</a><td> * @param {...*} var_args The arguments to be passed to the constructor.<tr><td><a name="l251" href="#l251">251</a><td> * @return {!Object} A new instance of the class given in {@code constructor}.<tr><td><a name="l252" href="#l252">252</a><td> */<tr><td><a name="l253" href="#l253">253</a><td>goog.functions.create = function(constructor, var_args) {<tr><td><a name="l254" href="#l254">254</a><td> /**<tr><td><a name="l255" href="#l255">255</a><td> * @constructor<tr><td><a name="l256" href="#l256">256</a><td> * @final<tr><td><a name="l257" href="#l257">257</a><td> */<tr><td><a name="l258" href="#l258">258</a><td> var temp = function() {};<tr><td><a name="l259" href="#l259">259</a><td> temp.prototype = constructor.prototype;<tr><td><a name="l260" href="#l260">260</a><td><tr><td><a name="l261" href="#l261">261</a><td> // obj will have constructor&#39;s prototype in its chain and<tr><td><a name="l262" href="#l262">262</a><td> // &#39;obj instanceof constructor&#39; will be true.<tr><td><a name="l263" href="#l263">263</a><td> var obj = new temp();<tr><td><a name="l264" href="#l264">264</a><td><tr><td><a name="l265" href="#l265">265</a><td> // obj is initialized by constructor.<tr><td><a name="l266" href="#l266">266</a><td> // arguments is only array-like so lacks shift(), but can be used with<tr><td><a name="l267" href="#l267">267</a><td> // the Array prototype function.<tr><td><a name="l268" href="#l268">268</a><td> constructor.apply(obj, Array.prototype.slice.call(arguments, 1));<tr><td><a name="l269" href="#l269">269</a><td> return obj;<tr><td><a name="l270" href="#l270">270</a><td>};<tr><td><a name="l271" href="#l271">271</a><td><tr><td><a name="l272" href="#l272">272</a><td><tr><td><a name="l273" href="#l273">273</a><td>/**<tr><td><a name="l274" href="#l274">274</a><td> * @define {boolean} Whether the return value cache should be used.<tr><td><a name="l275" href="#l275">275</a><td> * This should only be used to disable caches when testing.<tr><td><a name="l276" href="#l276">276</a><td> */<tr><td><a name="l277" href="#l277">277</a><td>goog.define(&#39;goog.functions.CACHE_RETURN_VALUE&#39;, true);<tr><td><a name="l278" href="#l278">278</a><td><tr><td><a name="l279" href="#l279">279</a><td><tr><td><a name="l280" href="#l280">280</a><td>/**<tr><td><a name="l281" href="#l281">281</a><td> * Gives a wrapper function that caches the return value of a parameterless<tr><td><a name="l282" href="#l282">282</a><td> * function when first called.<tr><td><a name="l283" href="#l283">283</a><td> *<tr><td><a name="l284" href="#l284">284</a><td> * When called for the first time, the given function is called and its<tr><td><a name="l285" href="#l285">285</a><td> * return value is cached (thus this is only appropriate for idempotent<tr><td><a name="l286" href="#l286">286</a><td> * functions). Subsequent calls will return the cached return value. This<tr><td><a name="l287" href="#l287">287</a><td> * allows the evaluation of expensive functions to be delayed until first used.<tr><td><a name="l288" href="#l288">288</a><td> *<tr><td><a name="l289" href="#l289">289</a><td> * To cache the return values of functions with parameters, see goog.memoize.<tr><td><a name="l290" href="#l290">290</a><td> *<tr><td><a name="l291" href="#l291">291</a><td> * @param {!function():T} fn A function to lazily evaluate.<tr><td><a name="l292" href="#l292">292</a><td> * @return {!function():T} A wrapped version the function.<tr><td><a name="l293" href="#l293">293</a><td> * @template T<tr><td><a name="l294" href="#l294">294</a><td> */<tr><td><a name="l295" href="#l295">295</a><td>goog.functions.cacheReturnValue = function(fn) {<tr><td><a name="l296" href="#l296">296</a><td> var called = false;<tr><td><a name="l297" href="#l297">297</a><td> var value;<tr><td><a name="l298" href="#l298">298</a><td><tr><td><a name="l299" href="#l299">299</a><td> return function() {<tr><td><a name="l300" href="#l300">300</a><td> if (!goog.functions.CACHE_RETURN_VALUE) {<tr><td><a name="l301" href="#l301">301</a><td> return fn();<tr><td><a name="l302" href="#l302">302</a><td> }<tr><td><a name="l303" href="#l303">303</a><td><tr><td><a name="l304" href="#l304">304</a><td> if (!called) {<tr><td><a name="l305" href="#l305">305</a><td> value = fn();<tr><td><a name="l306" href="#l306">306</a><td> called = true;<tr><td><a name="l307" href="#l307">307</a><td> }<tr><td><a name="l308" href="#l308">308</a><td><tr><td><a name="l309" href="#l309">309</a><td> return value;<tr><td><a name="l310" href="#l310">310</a><td> }<tr><td><a name="l311" href="#l311">311</a><td>};</table></pre></main><nav id="topnav"><div><div id="menubutton"><label for="sidenav-toggle">Menu</label></div><form id="searchbox"><div><input type="search" placeholder="Search" tabindex="1"></div></form></div></nav><nav id="sidenav"><input type="checkbox" id="sidenav-types-ctrl" /><input type="checkbox" id="sidenav-files-ctrl" /><input type="checkbox" id="sidenav-modules-ctrl" /><a id="sidenav-overview"><div><h4>Overview</h4></div></a><div id="sidenav-types"><label for="sidenav-types-ctrl"><h4>Types</h4></label><i>No data</i></div><div id="sidenav-modules"><label for="sidenav-modules-ctrl"><h4>Modules</h4></label><i>No data</i></div><div id="sidenav-files"><label for="sidenav-files-ctrl"><h4>Files</h4></label><i>No data</i></div><a href="license.html"><div><h4>License</h4></div></a></nav><div id="push-footer"></div></div><footer><a href="https://github.com/jleyba/js-dossier">Generated by dossier</a></footer><script src="../../../../types.js"></script><script src="../../../../dossier.js"></script>