Change them all into uppercase or lowercase, and then compare them
The character position of the first occurrence of the substring in the indexOf object
Use toLowerCase or toUpperCase
]
If you need to introduce external Js, you need to refresh to execute
]
[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>]
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
