如何获取数组中项的索引？

Question

var fruits = [ 'apple', 'banana', 'orange' ];

如何找到值"banana"的索引是什么？(当然,这是"1").

谢谢

Answer 1

如下所示:https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Objects/Array/IndexOf

if (!Array.prototype.indexOf)
{
  Array.prototype.indexOf = function(elt /*, from*/)
  {
    var len = this.length >>> 0;

    var from = Number(arguments[1]) || 0;
    from = (from < 0)
         ? Math.ceil(from)
         : Math.floor(from);
    if (from < 0)
      from += len;

    for (; from < len; from++)
    {
      if (from in this &&
          this[from] === elt)
        return from;
    }
    return -1;
  };
}

用法:

var fruits = [ 'apple', 'banana', 'orange' ];
var index = fruits.indexOf('banana');

将返回'1'