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

Question

If you have worked with JavaScript at any length you are aware that Internet Explorer does not implement the ECMAScript function for Array.prototype.indexOf() [includin

Answer 1

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

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

I recommend you use the implementation on MDC.