cabaret cabaret - 3 months ago 14
Javascript Question

For..In loops in javascript - key value pairs

I was wondering if there's a way to do something like a PHP foreach loop in JavaSript. The functionality I'm looking for is something like this: (PHP Snippet)

foreach($data as $key => $value) { }


I was looking at the JS
for..in
loop, but there seems to be no way to specify the
as
. If I do this with a 'normal' for loop (
for(var i = 0; i < data.length; i++
), is there a way to grab the key => value pairs?

Answer
for (var k in target){
    if (target.hasOwnProperty(k)) {
         alert("Key is " + k + ", value is" + target[k]);
    }
}

hasOwnProperty is used to check if your target really has that property, rather than having inherited it from its prototype. A bit simpler would be:

for (var k in target){
    if (typeof target[k] !== 'function') {
         alert("Key is " + k + ", value is" + target[k]);
    }
}

It just checks that k is not a method (as if target is array you'll get a lot of methods alerted, e.g. indexOf, push, pop,etc.)