Could someone please explain what each line of this function is doing?

Question

1.00/5 (3 votes)

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First Question:
every:

JavaScript

function (list, iterator) {
    if (list == null) return true;
    	iterator = iterator || this.identity;
    	var keys = list.length !== +list.length && this.keys(list),
    		length = (keys || list).length,
    		index, currentKey;
    	for (index = 0; index < length; index++) {
    		currentKey = keys ? keys[index] : index;
    		if (!iterator(list[currentKey], currentKey, list)) return false;
    	}
    	return true;
    
    }

Second Question (no need for line by line instruction):

each:

JavaScript

function (list, iterator) {
    var i, length;
    if (isArrayLike(list)) {
    	for (i = 0, length = list.length; i < length; i++) {
    		iterator(list[i], i, list);
    	}
    }
    else {
    	var keys = Object.keys(list);
    	for (i = 0, length = keys.length; i < length; i++) {
    		iterator(list[keys[i]], keys[i], list);
    	}
    }
}

How come in this function you have to do the iterator over all three of the (list[i], i, and list)?

Thanks!

Posted 17-Sep-15 4:21am

Member 11991766

Updated 17-Sep-15 5:07am

Patrice T

v2

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OriginalGriff · Answer 1 · 2015-09-17T04:33:00

Do you have any idea how much work explaining code line by line is?
Every single line needs a paragraph of explanation! For example:

int next = r.Next();

Create a new variable called "next" which can hold a integer value. From the previously declared Random instance "r", call the "Next" method to get a new random number, and assign it to the "next" variable.

Can you imagine how long it would take us to explain even a very short code fragment like your example, line by line?

No. It is not going to happen. If you have a specific problem, then ask a question about it. But think first - would you want to sit down for 45 minutes and type up a line-by-line description for no good reason?

Richard MacCutchan · Answer 2 · 2015-09-17T06:01:00

Solution 4

Go to http://www.w3schools.com/js/default.asp[^] and you will be able to learn all about it.

Posted 17-Sep-15 6:01am

Richard MacCutchan

Patrice T · Answer 3 · 2015-09-17T05:03:00

What you request is a huge work because of your little understanding of this code. The fact that you ask this makes that you will need a lot of explanations.

First solution:
- Hire a consultant or ask a friend/teacher more skilled than you.

Second Solution:
- Use the debugger to see the code execute, you will see what it does. It may be enough for you to understand it. By seeing what it does, you may understand why.

Could someone please explain what each line of this function is doing?

3 solutions

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