2817

How can I find out the position of an item contained by an array?

Question:

I know the name of the item and would like to know its position in the array, how would I do that?

Answer1:

["a","b","c","d","e"].indexOf("c") 2

Answer2:

You could loop through the array:

var array = ['item1', 'item2', 'item3']; function findIndex(array, item) { for (var i = 0; i < array.length; i++) { if (array[i] === item) { return i; } } return -1; } alert(findIndex(array, 'item2'));

Or using a comparer function for more complex types:

var array = ['item1', 'item2', 'item3']; function findIndex(array, comparer) { for (var i = 0; i < array.length; i++) { if (comparer(array[i])) { return i; } } return -1; } var index = findIndex(array, function(item) { return item === 'item2' ; });

Answer3:

Use the indexOf method of Array. If it's not there add it (code example <a href="http://soledadpenades.com/2007/05/17/arrayindexof-in-internet-explorer/" rel="nofollow">here</a> or other places).

If you want to find a value by its name property, do this:

for (var i = 0; i < this.length; i++) { if(this[i].name == name) { return i; } } return -1;

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