Tag: indexof

Just a quick note on how to deal with another one of the IE/Javascript deficiencies that make our lives so much easier(!) – IE from versions 8 backwards doesn’t support the indexOf() function for arrays, e.g.

var myArray = ['Apple','Banana','Orange'];
alert(myArray.indexOf('Orange'));  //alerts '2', but not in IE <=8

Thankfully, there are easy ways to fix this:

1. the JQuery $.inArray() function, e.g.

   alert($.inArray('Orange',myArray);

2. Defining the indexOf function (before you call it!) if it doesn’t exist – taken from MDN

   if (!Array.prototype.indexOf) {
     Array.prototype.indexOf = function (searchElement /*, fromIndex */ ) {
       'use strict';
       if (this == null) {
         throw new TypeError();
       }
       var n, k, t = Object(this),
           len = t.length >>> 0;
   
       if (len === 0) {
         return -1;
       }
       n = 0;
       if (arguments.length > 1) {
         n = Number(arguments[1]);
         if (n != n) { // shortcut for verifying if it's NaN
           n = 0;
         } else if (n != 0 && n != Infinity && n != -Infinity) {
           n = (n > 0 || -1) * Math.floor(Math.abs(n));
         }
       }
       if (n >= len) {
         return -1;
       }
       for (k = n >= 0 ? n : Math.max(len - Math.abs(n), 0); k < len; k++) {
         if (k in t && t[k] === searchElement) {
           return k;
         }
       }
       return -1;
     };
   }