blocks|key|1190371|text|这样做..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1190372|if+(!Array.prototype.indexOf)+{

}|code-block|syntax|javascript|1190373|作为recommended+compatibility+by+MDC。|offset|length|1190374|一般来说，浏览器检测代码是一个很大的禁忌。|1190375|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Objects/Array/IndexOf^0|0|0|2|W|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

Do it like this...

<pre><code>if (!Array.prototype.indexOf) {

}
</code></pre>

As <a href="https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Objects/Array/IndexOf" rel="noreferrer">recommended compatibility by MDC</a>.

In general, browser detection code is a big no-no.

blocks|key|1190537|text|或者，您可以使用jQuery+1.2+inArray+function，它应该可以跨浏览器工作：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1190538|jQuery.inArray(+value,+array+[,+fromIndex+]+)|code-block|syntax|javascript|1190539|entityMap|0|LINK|mutability|MUTABLE|url|http://api.jquery.com/jQuery.inArray/^0|8|R|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Alternatively, you could use the <a href="http://api.jquery.com/jQuery.inArray/" rel="noreferrer">jQuery 1.2 inArray function</a>, which should work across browsers:

<pre><code>jQuery.inArray( value, array [, fromIndex ] )
</code></pre>

blocks|key|1190603|text|underscore.js库有一个indexOf函数，您可以使用它来代替：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1190604|_.indexOf([1,+2,+3],+2)|code-block|syntax|javascript|1190605|entityMap|0|LINK|mutability|MUTABLE|url|http://documentcloud.github.com/underscore/#indexOf^0|H|7|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

The underscore.js library has an <a href="http://documentcloud.github.com/underscore/#indexOf">indexOf</a> function you can use instead:

<pre><code>_.indexOf([1, 2, 3], 2)
</code></pre>

blocks|key|1405761|text|您应该检查它是否不是使用if+(!Array.prototype.indexOf)定义的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1405762|此外，您的indexOf实现也不正确。您必须在if+(this[i]+==+obj)语句中使用===而不是==，否则根据您的实现，[4,"5"].indexOf(5)将为1，这是不正确的。|1405763|我建议您使用the+implementation+on+MDC。|1405764|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Objects/Array/IndexOf#Compatibility^0|C|T|0|5|7|N|J|1B|3|1H|2|1T|I|0|6|P|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|15|8|@]|D|@$9|16|A|17|1|18]]|E|$]]|$1|J|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

You should check if it's not defined using <code>if (!Array.prototype.indexOf)</code>.

Also, your implementation of <code>indexOf</code> is not correct. You must use <code>===</code> instead of <code>==</code> in your <code>if (this[i] == obj)</code> statement, otherwise <code>[4,"5"].indexOf(5)</code> would be 1 according to your implementation, which is incorrect.

I recommend you use <a href="https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Objects/Array/IndexOf#Compatibility" rel="noreferrer">the implementation on MDC</a>.

blocks|key|1190748|text|有Mozilla官方解决方案：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1190749|(function()+{
++++/**Array*/
++++//+Production+steps+of+ECMA-262,+Edition+5,+15.4.4.14
++++//+Reference:+http://es5.github.io/#x15.4.4.14
++++if+(!Array.prototype.indexOf)+{
++++++++Array.prototype.indexOf+=+function(searchElement,+fromIndex)+{
++++++++++++var+k;
++++++++++++//+1.+Let+O+be+the+result+of+calling+ToObject+passing
++++++++++++//++++the+this+value+as+the+argument.
++++++++++++if+(null+===+this+%7C%7C+undefined+===+this)+{
++++++++++++++++throw+new+TypeError('"this"+is+null+or+not+defined');
++++++++++++}
++++++++++++var+O+=+Object(this);
++++++++++++//+2.+Let+lenValue+be+the+result+of+calling+the+Get
++++++++++++//++++internal+method+of+O+with+the+argument+"length".
++++++++++++//+3.+Let+len+be+ToUint32(lenValue).
++++++++++++var+len+=+O.length+>>>+0;
++++++++++++//+4.+If+len+is+0,+return+-1.
++++++++++++if+(len+===+0)+{
++++++++++++++++return+-1;
++++++++++++}
++++++++++++//+5.+If+argument+fromIndex+was+passed+let+n+be
++++++++++++//++++ToInteger(fromIndex);+else+let+n+be+0.
++++++++++++var+n+=+%2BfromIndex+%7C%7C+0;
++++++++++++if+(Math.abs(n)+===+Infinity)+{
++++++++++++++++n+=+0;
++++++++++++}
++++++++++++//+6.+If+n+>=+len,+return+-1.
++++++++++++if+(n+>=+len)+{
++++++++++++++++return+-1;
++++++++++++}
++++++++++++//+7.+If+n+>=+0,+then+Let+k+be+n.
++++++++++++//+8.+Else,+n<0,+Let+k+be+len+-+abs(n).
++++++++++++//++++If+k+is+less+than+0,+then+let+k+be+0.
++++++++++++k+=+Math.max(n+>=+0+?+n+:+len+-+Math.abs(n),+0);
++++++++++++//+9.+Repeat,+while+k+<+len
++++++++++++while+(k+<+len)+{
++++++++++++++++//+a.+Let+Pk+be+ToString(k).
++++++++++++++++//+++This+is+implicit+for+LHS+operands+of+the+in+operator
++++++++++++++++//+b.+Let+kPresent+be+the+result+of+calling+the
++++++++++++++++//++++HasProperty+internal+method+of+O+with+argument+Pk.
++++++++++++++++//+++This+step+can+be+combined+with+c
++++++++++++++++//+c.+If+kPresent+is+true,+then
++++++++++++++++//++++i.++Let+elementK+be+the+result+of+calling+the+Get
++++++++++++++++//++++++++internal+method+of+O+with+the+argument+ToString(k).
++++++++++++++++//+++ii.++Let+same+be+the+result+of+applying+the
++++++++++++++++//++++++++Strict+Equality+Comparison+Algorithm+to
++++++++++++++++//++++++++searchElement+and+elementK.
++++++++++++++++//++iii.++If+same+is+true,+return+k.
++++++++++++++++if+(k+in+O+&&+O[k]+===+searchElement)+{
++++++++++++++++++++return+k;
++++++++++++++++}
++++++++++++++++k%2B%2B;
++++++++++++}
++++++++++++return+-1;
++++++++};
++++}
})();|code-block|syntax|javascript|1190750|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf^0|F|2M|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

There is Mozilla official solution:
<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf">https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf</a>

<pre><code>(function() {
 /**Array*/
 // Production steps of ECMA-262, Edition 5, 15.4.4.14
 // Reference: http://es5.github.io/#x15.4.4.14
 if (!Array.prototype.indexOf) {
 Array.prototype.indexOf = function(searchElement, fromIndex) {
 var k;
 // 1. Let O be the result of calling ToObject passing
 // the this value as the argument.
 if (null === this || undefined === this) {
 throw new TypeError('"this" is null or not defined');
 }
 var O = Object(this);
 // 2. Let lenValue be the result of calling the Get
 // internal method of O with the argument "length".
 // 3. Let len be ToUint32(lenValue).
 var len = O.length &gt;&gt;&gt; 0;
 // 4. If len is 0, return -1.
 if (len === 0) {
 return -1;
 }
 // 5. If argument fromIndex was passed let n be
 // ToInteger(fromIndex); else let n be 0.
 var n = +fromIndex || 0;
 if (Math.abs(n) === Infinity) {
 n = 0;
 }
 // 6. If n &gt;= len, return -1.
 if (n &gt;= len) {
 return -1;
 }
 // 7. If n &gt;= 0, then Let k be n.
 // 8. Else, n&lt;0, Let k be len - abs(n).
 // If k is less than 0, then let k be 0.
 k = Math.max(n &gt;= 0 ? n : len - Math.abs(n), 0);
 // 9. Repeat, while k &lt; len
 while (k &lt; len) {
 // a. Let Pk be ToString(k).
 // This is implicit for LHS operands of the in operator
 // b. Let kPresent be the result of calling the
 // HasProperty internal method of O with argument Pk.
 // This step can be combined with c
 // c. If kPresent is true, then
 // i. Let elementK be the result of calling the Get
 // internal method of O with the argument ToString(k).
 // ii. Let same be the result of applying the
 // Strict Equality Comparison Algorithm to
 // searchElement and elementK.
 // iii. If same is true, return k.
 if (k in O &amp;&amp; O[k] === searchElement) {
 return k;
 }
 k++;
 }
 return -1;
 };
 }
})();
</code></pre>

blocks|key|1405941|text|我建议任何想要寻找缺失功能的人：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1405942|http://code.google.com/p/ddr-ecma5/|offset|length|1405943|它为较老的浏览器带来了大多数缺失的ecma5功能:)|1405944|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|Z|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@$D|Q|E|R|1|S]]|A|$]]|$1|F|3|G|5|6|7|T|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|C]]]]

I would recommend this to anyone looking for missing functionality: 

<a href="http://code.google.com/p/ddr-ecma5/" rel="noreferrer">http://code.google.com/p/ddr-ecma5/</a>

It brings in most of the missing ecma5 functionality to older browers :)

blocks|key|1406003|text|这是我的实现。本质上，在页面上的任何其他脚本之前添加此脚本。我还添加了trim函数，该函数似乎在很多框架中都有使用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1406004||code-block|syntax|javascript|1406005|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This was my implementation. Essentially, add this before any other scripts on the page. i.e. in your master for a global solution for Internet Explorer 8. I also added in the trim function which seems to be used in allot of frameworks. 

<pre><code>&lt;!--[if lte IE 8]&gt;
&lt;script&gt;
 if (!Array.prototype.indexOf) {
 Array.prototype.indexOf = function(obj, start) {
 for (var i = (start || 0), j = this.length; i &lt; j; i++) {
 if (this[i] === obj) {
 return i;
 }
 }
 return -1;
 };
 }

 if(typeof String.prototype.trim !== 'function') {
 String.prototype.trim = function() {
 return this.replace(/^\s+|\s+$/g, '');
 };
 };
&lt;/script&gt;
&lt;![endif]--&gt;
</code></pre>

blocks|key|1406067|text|这对我很管用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1406068|if+(!Array.prototype.indexOf)+{
++Array.prototype.indexOf+=+function(elt+/*,+from*/)+{
++++var+len+=+this.length+>>>+0;

++++var+from+=+Number(arguments[1])+%7C%7C+0;
++++from+=+(from+<+0)?+Math.ceil(from)+:+Math.floor(from);
++++if+(from+<+0)
++++from+%2B=+len;

++++for+(;+from+<+len;+from%2B%2B)+{
++++++if+(from+in+this+&&+this[from]+===+elt)
++++++++return+from;
++++}
++++return+-1;
++};
}|code-block|syntax|javascript|1406069|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

it works for me.

<pre><code>if (!Array.prototype.indexOf) {
 Array.prototype.indexOf = function(elt /*, from*/) {
 var len = this.length &gt;&gt;&gt; 0;

 var from = Number(arguments[1]) || 0;
 from = (from &lt; 0)? Math.ceil(from) : Math.floor(from);
 if (from &lt; 0)
 from += len;

 for (; from &lt; len; from++) {
 if (from in this &amp;&amp; this[from] === elt)
 return from;
 }
 return -1;
 };
}
</code></pre>

blocks|key|1406012|text|使用Underscore.js|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1406013|var+arr=['a','a1','b']++_.filter(arr,+function(a){+return+a.indexOf('a')+>+-1;+})|offset|length|style|CODE|1406014|entityMap^0|0|0|29|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

With the Underscore.js

<code>var arr=['a','a1','b'] 
_.filter(arr, function(a){ return a.indexOf('a') &gt; -1; })</code>

If you have worked with JavaScript at any length you are aware that Internet&nbsp;Explorer does not implement the ECMAScript function for Array.prototype.indexOf() [including Internet&nbsp;Explorer&nbsp;8]. It is not a huge problem, because you can extend the functionality on your page with the following code.

<pre><code>Array.prototype.indexOf = function(obj, start) {
 for (var i = (start || 0), j = this.length; i &lt; j; i++) {
 if (this[i] === obj) { return i; }
 }
 return -1;
}
</code></pre>

When should I implement this?

Should I wrap it on all my pages with the following check, which checks if the prototype function exists and if not, go ahead and extend the Array prototype?

<pre><code>if (!Array.prototype.indexOf) {

 // Implement function here

}
</code></pre>

Or do browser check and if it is Internet&nbsp;Explorer then just implement it?

<pre><code>//Pseudo-code

if (browser == IE Style Browser) {

 // Implement function here

}
</code></pre>

How to fix Array indexOf() in JavaScript for Internet Explorer browsers

如果您曾经使用过JavaScript，您就会知道Internet Explorer没有为Array.prototype.indexOf()实现ECMAScript函数，包括Internet Explorer 8。这不是一个大问题，因为您可以使用以下代码扩展页面上的功能。Array.prototype.indexOf = function(obj, start) {     for (var i =

问如何在Internet Explorer浏览器的JavaScript中修复数组indexOf()
EN

回答 9

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问如何在Internet Explorer浏览器的JavaScript中修复数组indexOf()EN

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问如何在Internet Explorer浏览器的JavaScript中修复数组indexOf()
EN