JavaScript indexOf ignores case_javascript tips

Let me introduce to you how to make the indexOf function in JavaScript ignore case.
Change them all into uppercase or lowercase, and then compare.
This is a relatively simple method!
The character position where the substring appears for the first time in the indexOf object.
Use toLowerCase or toUpperCase as follows:

[Ctrl A Select all Note: If you need to introduce external Js, you need to refresh to execute

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Or look at the following How to extend the indexof function:

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If you need to introduce external Js, you need to refresh to execute
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The following is compatible with the original indexOf Function, you can add the indexOf function operation that can be directly used to ignore case javascript.

[Ctrl A select all Note: <script> var testStr = 'ABCDEF'; var subStr = 'bcd'; alert(testStr.toLowerCase().indexOf(subStr.toLowerCase())); testStr = 'AbCdEf'; alert(testStr.toLowerCase().indexOf(subStr.toLowerCase())); </script>If you need to introduce external Js, you need to refresh to execute <script> String.prototype.indexOf = function(f,m){ var mm = (m == false) ? "i":""; var re = eval("/"+ f +"/"+mm); var rt = this.match(re); return (rt == null) ? -1:rt.index; } var test = "absnegKIugfkalg"; alert(test.indexOf("kiu",false)); </script>]