JavaScript: IndexOf sanity check
IndexOf returns the position in a data type or structure where the first occurence of a passed-in argument appears.
If no occurence is found, it returns "-1".
Before embracing regular expressions, I used this heavily for assessing strings.
However, a friend reminded me recently that this method works with arrays as well as strings**
With an array, the method returns the index of the array item where the value occurs.
In a string, it's the character position.
Here's the caveat...it doesn't appear to work in IE.
Here's a quick test to demonstrate how it works (or fails) in your browser of choice...
Examples:
<![CDATA[
<script>
function testArray(){
var arr = [ 111, 222, 333 ];
var msg = '';
/* access the 1st element, then find it's position in the array via indexOf */
alert(arr[0]); /* 111 */
alert(arr.indexOf(111)); /* 0 */
/* access an element, then find it's position in the array via indexOf */
alert(arr[2]); /* "333" */
alert(arr.indexOf(333)); /* 2 */
/* failure: attempt to accesses something that doesn't exist in the array */
alert(arr[10]); /* undefined */
alert(arr.indexOf(999)); /* -1 */
}
</script>
]]>
<![CDATA[
<script>
function testString(){
var str = 'This is a test string';
alert(str.indexOf('test')); /* 10 */
alert(str.indexOf('fail')); /* -1 */
}
</script>
]]>