JavaScript for…in vs for

Question

Do you think there is a big difference in for...in and for loops? What kind of \"for\" do you prefer to use and why?

Let\'s say we have an array of associative array

Answer 1

Be careful!!! I am using Chrome 22.0 in Mac OS and I am having problem with the for each syntax.

I do not know if this is a browser issue, javascript issue or some error in the code, but it is VERY strange. Outside of the object it works perfectly.

var MyTest = {
    a:string = "a",
    b:string = "b"
};

myfunction = function(dicts) {
    for (var dict in dicts) {
        alert(dict);
        alert(typeof dict); // print 'string' (incorrect)
    }

    for (var i = 0; i < dicts.length; i++) {
        alert(dicts[i]);
        alert(typeof dicts[i]); // print 'object' (correct, it must be {abc: "xyz"})
    }
};

MyObj = function() {
    this.aaa = function() {
        myfunction([MyTest]);
    };
};
new MyObj().aaa(); // This does not work

myfunction([MyTest]); // This works