testing rewriting a simple loop with an immediate function

Question

I'm not sure why I'm getting an error on the following snippet (adapted from JavaScript closure inside loops – simple practical example):

var funcs = {};
for (var i = 0; i < 3; i++) {          // let's create 3 functions
    funcs[i] = (function(n) {            // and store them in funcs
        console.log("My value: " + n); // each should log its value.
    })(i);
}
for (var j = 0; j < 3; j++) {
    funcs[j]();                        // and now let's run each one to see
}

It seems like this should run ok; I know this is just something I don't fully get.

Here is the errror I get: enter image description here

thx for any help

you set `funcs[i]` to the result of a function, not the function itself. You're calling it with `i` as the parameter. — Dave, Aug 23 '13 at 16:51
future reference: `console.log(funcs)`: check if it contains what you expect it to contain. — Dave, Aug 23 '13 at 16:51
@MattGreer I don't think it's really worth an answer. Feels like there will be a lot of duplicates. — Dave, Aug 23 '13 at 16:54

score 2 · Accepted Answer · answered Aug 23 '13 at 16:53

You need to return a function, rather than a result of the function. Try:

funcs[i] = (function(n) {
  return function() { 
    console.log("My value: " + n); 
  }
})(i);

Example:

> var funcs = {};
for (var i = 0; i < 3; i++) {
  funcs[i] = (function(n) { 
    return function() {console.log("My value: " + n);} 
  })(i);
}
for (var j = 0; j < 3; j++) {
  funcs[j]();                
}
My value: 0
My value: 1
My value: 2

testing rewriting a simple loop with an immediate function

1 Answers1