jQuery .forEach() causing error, "undefined is not a function"

Question

I'm getting the error, undefined is not a function for the line entries.forEach(function(e) { and I don't know why. Can anyone help?

I'm certain that entries is defined as the prototype below when I pass it to the function.

This is the function I'm working on:

function score_relevance3(entries, usr_tags) {

    entries.forEach(function(e) 
    {
        entries[e].count = 0;
        entries[e].tags.forEach(function(i) 
        {
            usr_tags.forEach(function(f) 
            {
                if (entries[e].tags[i] === usr_tags[f]) 
                {
                    entries[e].count++;
                }
            });
        });
    });

    return entries;
}

Here is a prototype of my entries object:

entries = {
"1":{"tags":["1","2"]},
"2":{"tags":["1","3","2"]},
"3":{"tags":["1","2"]},
"4":{"tags":["1","2"]},
"5":{"tags":["1","2"]},
"6":{"tags":["4","5","6","2"]},
"7":{"tags":["4","7"]},
"8":{"tags":["4","8","3"]},
"9":{"tags":["4","9"]}
};

or `for(prop in entries) { if (entries.hasOwnProperty(prop) { ... } }`, http://stackoverflow.com/questions/8312459/iterate-through-object-properties — jdphenix, Jan 22 '15 at 04:01
`forEach` requires an array object. Are you sure you are passing an array object to `entries`? http://www.tutorialspoint.com/javascript/array_foreach.htm — d.yuk, Jan 22 '15 at 04:23

score 2 · Answer 1 · answered Jan 22 '15 at 04:23

2

Like elclanrs mentions in the comment, you can't call forEach on an object, only an array. If you want to go through entries, use:

for (entry in entries) { ...

answered Jan 22 '15 at 04:23

lhoworko

1,191
2
13
24

score 0 · Answer 2 · answered Jan 22 '15 at 04:12

The reason is simple. For instance, if you have an object, foo, and you try to call foo.bar(), then, if bar is undefined, then you cannot use it as a function and you will get the error of

undefined is not a function

Here

entries.forEach(function(e) {

I believe forEach does not exist and you have the error for the above mentioned reasons. Try this:

console.log(entries.forEach);

Is it undefined?

jQuery .forEach() causing error, "undefined is not a function"

2 Answers2