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JavaScript Uses for Closures

Dee K
Dee K
17,815 Points
Posted by Dee K
Dee K
17,815 Points

Why do we need closure for the function we use inside the for loop?

I am curious as to why this function wouldn't work when we reference it in the for loop.

function createHandler(name) {
    console.log(name);
  }

Why is it that we need closure and need to use this function instead?

function createHandler(name) {
  return function() {
     console.log(name);
  }
}

Any explanation would be greatly appreciated!

1 Answer

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

Those functions do different things. The first one just calls console.log, almost as if it were a replacement for it.

But the second one just defines a function that will call it when invoked. And with a specific argument.

So they would be used in different ways.

// the first one:
createHandler("example one");  // this logs the words "example one" on the console

// the second one:
var myfunc = createHandler("example two");  // nothing happens ... yet
myfunc();                                   // but now this logs "example two" on the console