JavaScript Array `console.log` output behaviour

Question

When we run a forEach() function on an array depending on the way the index & items are arranged dev tools returns different output. I'm wondering if anyone knows why this happens.

Please see the images below:

When I swap the variables over from item, index to index, item the output looks different.

I wonder what makes the variable output different and why.

Just as a note: I only see this behavior in Chrome. Firefox makes no difference between both cases. You can also shorten the example to console.log( "a", 1 ) vs console.log( 1, "a", ). — Sirko
– Sirko, Commented Jul 3, 2017 at 7:04
I don't understand the question. Why are you puzzled by the output changing when you swap the parameters? — Roland Mai
– Roland Mai, Commented Jul 3, 2017 at 7:19
There is no difference. You are just printing them in the console like that. — Ram_T
– Ram_T, Commented Jul 3, 2017 at 7:20
@Candide I think this is a good question even though it might look trivial. — immysl
– immysl, Commented Jul 3, 2017 at 7:25
This has nothing to do with forEach. Please edit your question to include what console implementation (what JS environment) you are using. And it would help if you could post the code/output as text, not as paintings. — Bergi
– Bergi, Commented Jul 4, 2017 at 5:36

Lawrence_NT · Accepted Answer · 2017-07-04 05:30:54Z

1

According to MDN documentation regarding console.log here

This explains that the first parameter is handled either as an object or a string. Subsequent parameters are handled as objects.

I assume this forces the strings, from the second parameter onward, to print with quotes.

To read more about the chrome-console, visit this page

answered Jul 4, 2017 at 5:30

Lawrence_NT

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Ebrahim Poursadeqi · Accepted Answer · 2017-07-03 07:07:30Z

0

as here says

Syntax
console.log(obj1 [, obj2, ..., objN]);
console.log(msg [, subst1, ..., substN]);
Parameters

obj1 ... objN
A list of JavaScript objects to output. The string representations of each of these objects are appended together in the order listed and

output.

and when you write consoloe.log(item,index) it first write item and then index and vice versa

answered Jul 3, 2017 at 7:07

Ebrahim Poursadeqi

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