CODEWITHSUNDEEP
javascript
Iditarod1973
Iditarod1973

Reputation: 43

Global Object and assignment - why does it recognize the assignment?

When I run in the console, I don't quite follow why it yields a result of zero. I thought both MyObject and myFunc are global. What concept am I missing to understand this properly?

myObject = {
length: 400,
};

function myFunc () {
return console.log(this.length);

}

myFunc(myObject.length); // equals zero

Upvotes: 0

Views: 32

Answers (2)

War10ck
War10ck

Reputation: 12508

You're passing the object as a parameter, but you're not receiving it in the function. this in the context of myFunc is not the object myObject. It is the window object.

To achieve what you're trying to do, modify your code like so:

myObject = {
    length: 400,
};

function myFunc (obj) {
    return console.log(obj.length); 
}

myFunc(myObject); // equals zero

Note:

To verify that this is the window object, see this fiddle where I've modified your console line to be return console.log(this);. The console outputs the Window object.

Demonstration Fiddle

Upvotes: 0

T.J. Crowder
T.J. Crowder

Reputation: 1074969

It's showing you the value of window.length (which is the number of frames/iframes in the document). To have myFunc show you the value of the length of the object you pass into it, you'd have to use that argument:

function myFunc (obj) {
    return console.log(obj.length);
}

If you're trying to explore implicit globals (your myObject is an implicit global; they're a Bad Thing(tm)), then myFunc should be called with no arguments and should use myObject.length or possibly this.myObject.length (which come to the same thing).

Upvotes: 2

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