jQuery.inArray()
Search for a specified value within an array and return its index (or -1 if not found).
jQuery.inArray(value, array, fromIndex)🡢 Number
value
| Anything | The value to search for. |
array
| Array | An array through which to search. |
fromIndex
| Number | The index of the array at which to begin the search. The default is 0, which will search the whole array. |
The $.inArray() method is similar to JavaScript's native .indexOf() method in that it returns -1 when it doesn't find a match. If the first element within the array matches value, $.inArray() returns 0.
Because JavaScript treats 0 as loosely equal to false (i.e. 0 == false, but 0 !== false), to check for the presence of value within array, you need to check if it's not equal to (or greater than) -1.
The comparison between values is strict. The following will return -1 (not found) because a number is being searched in an array of strings:
$.inArray(5 + 5, ["8", "9", "10", 10 + ""]);
Report the index of some elements in the array.
JS
<div>"John" found at <span></span></div>
<div>4 found at <span></span></div>
<div>"Karl" not found, so <span></span></div>
<div>"Pete" is in the array, but not at or after index 2, so <span></span></div>
CSS
div {
color: blue;
}
span {
color: red;
}
HTML
var arr = [4, "Pete", 8, "John"];
var $spans = $("span");
$spans.eq(0).text(jQuery.inArray("John", arr));
$spans.eq(1).text(jQuery.inArray(4, arr));
$spans.eq(2).text(jQuery.inArray("Karl", arr));
$spans.eq(3).text(jQuery.inArray("Pete", arr, 2));
DEMO