Returning values out of for loop in javascript

Question

I have the following function:

  function getId(a){
    var aL = a.length;
    for(i = 0; i < aL; i++ ){
      return a[i][2].split(":", 1)[0];
    }    
  }

and when using console.log() within the function instead of return I get all of the values in the loop, and the same goes for document.write. How can I access these values as a string for use in another section of my code?

Thank you in advance.

The return statement immediately exits a function, returning the value of the expression that follows it. If you use a return statement in a loop without some sort of conditional like that it will preform the first pass and then exit. You need to collect them in a variable and return the variable after the loop. As others have suggested you'll probably want to store them in an array. — Useless Code
– Useless Code, Commented Nov 15, 2011 at 5:31
Thanks Useless Code after looking into this a bit deeper I see where I was mistaken. Thank you — jeffreynolte
– jeffreynolte, Commented Nov 15, 2011 at 5:34

Gabi Purcaru · Accepted Answer · 2011-11-15 05:20:16Z

16

You can do that with yield in newer versions of js, but that's out of question. Here's what you can do:

function getId(a){
  var aL = a.length;
  var values = [];
  for(i = 0; i < aL; i++ ){
    values.push(a[i][2].split(":", 1)[0]);
  }    
  return values.join('');
}

answered Nov 15, 2011 at 5:20

Gabi Purcaru

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2 Comments

fncomp Over a year ago

Shouldn't that be var values = [];?

fabpico Over a year ago

yield link is dead. New is developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/…. Can't edit due to full edit queue.

fncomp · Accepted Answer · 2011-11-15 05:21:02Z

2

You gotta cache the string and return later:

function getId(a){
    var aL = a.length;
    var output = '';
    for(var i = 0; i < aL; i++ ){
       output += a[i][2].split(":", 1)[0];
    }    
    return output;
}

answered Nov 15, 2011 at 5:21

fncomp

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Comments

Awesome · Accepted Answer · 2017-09-19 19:25:49Z

0

The return statement breaks the loop once it is executed. Therefore consider putting the return statement outside the loop.
Since you want to return a string, you will create a variable and assign it to an empty string.(This is where will append/add results from the loop.)
return the string variable.

So final code will look like...

function getId(a){
    var result = '';
    var aL = a.length;
    for(i = 0; i < aL; i++ ){
      result += a[i][2].split(":", 1)[0];
    } 
    return result;
  }

answered Sep 19, 2017 at 19:25

Awesome

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