var arr = ['test','hello'];
is there a javascript native call to get index of some value('hello') in an array?
Add a comment
|
3 Answers
arr.indexOf("hello");
The indexOf method isn't supported in all browsers (it was added in JavaScript 1.6), but you can use the following code to make it work in those that don't (code from the MDC page for 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;
};
}
Comments
In javascript 1.6+ you can use .indexOf():
var index = arr.indexOf('hello');
In earlier versions you would just have to loop through the array yourself.
Interestingly, alert([].indexOf) in Chrome gives you the implementation:
function indexOf(element, index) {
var length = this.length;
if (index == null) {
index = 0;
} else {
index = (_IsSmi(IS_VAR(index)) ? index : ToInteger(index));
if (index < 0) index = length + index;
if (index < 0) index = 0;
}
for (var i = index; i < length; i++) {
var current = this[i];
if (!(typeof(current) === 'undefined') || i in this) {
if (current === element) return i;
}
}
return -1;
}
Don't ask me what _IsSmi(IS_VAR(index)) does though...
7 Comments
omg
where to see my javascript version?
Greg
the best thing to do is just see if it's supported - if (typeof [].indexOf == 'undefined') { you don't have it }
omg
It's suppored,but still don't know javascript version:(
Greg
You'd need to check the version of your browser and look it up
cwallenpoole
Kudos for finding the actual implementation. Definitely worth a +1
|
arr.indexOf('hello');I don't know if it works on IE though (It surely works on Firefox and Webkit).
:-D
1 Comment
NawaMan
I really don't know why do I get vote down .... My answer is not much different from other (surely not wrong). ???