JS function implementation method for determining whether an array contains a certain element

JS function implementation method for determining whether an array contains a certain element

 Array.prototype.contains = function(obj) { var i = this.length; while (i--) { if (this[i] === obj) { return true; } } return false;}

or

 Array.prototype.contains = function(element) { for (var i = 0; i < this.length; i++) { if (this[i] == element) { return true; } } return false;}

or

 Array.prototype.in_array = function(e) { for(i=0; i<this.length && this[i]!=e; i++); return !(i==this.length);}

Another big bull wrote this:

 Array.prototype.S = String.fromCharCode(2);Array.prototype.in_array = function(e) { var r = new RegExp(this.S+e+this.S); return (r.test(this.S+this.join(this.S)+this.S));}

How to use it is:

var arr=["a","b"];

alert(arr.in_array("a"))

It is said that while iterating is the fastest method in JS. I don’t know if it is true.

http://stackoverflow.com/questions/237104/javascript-array-containsobj

The discussion here is very intense, it is recommended to take a look. If you use jQuery, you can directly use jQuery to implement it. Reference address:

http://api.jquery.com/jQuery.inArray/

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