Finding last iteration in for in loop javascript

Question

I am having following sample code

   var obj = { a: {b:1, c:3 }, d :{f:5}}
        var string = "";
        for(var key in obj){
            for(var subkey in obj[key]){
             string += subkey + "="+ obj[key][subkey] + "&";
             //for last iteration "&" should not be added.
         }
    }
   console.log(string);

output is

b=1&c=3&f=5&

Required Output

b=1&c=3&f=5

In this particular case, the easiest thing to do would be to simply take a substring of your output string, to remove the '&'. — Stilltorik, May 22 '13 at 09:49
If you're using jQuery, let that to jQuery. Don't compose the URL yourself — John Dvorak, May 22 '13 at 09:49
If it is for transmitting parameters and this is the final query string, just leave the `&` at the end. It won´t matter. — Amberlamps, May 22 '13 at 09:50
`string += "&"+subkey + "="+ obj[key][subkey];` and at the end do `... string.substring(1)` — mplungjan, May 22 '13 at 09:52
Not a contribution to the question but to your case: are you sure your subkeys are unique (e.g. if subkey b in key a there cannot be a subkey b in key d)? — Menno, May 22 '13 at 09:59

score 9 · Accepted Answer · answered May 22 '13 at 09:55

9

An alternative approach would be:

var obj = { a: {b:1, c:3 }, d :{f:5}},
  array = [];
for(var key in obj){
  for(var subkey in obj[key]){
    array.push(subkey + "="+ obj[key][subkey]);
  }
}
console.log(array.join('&'));

answered May 22 '13 at 09:55

Rob Johnstone

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9
14

score 4 · Answer 2 · edited May 23 '17 at 12:34

4

If you're creating the query-part of a url, I'd go with the solution provided here: How to create query parameters in Javascript?

If not, just drop the encoding-part :)

Copy of relevant code:

// Usage:
//   var data = { 'first name': 'George', 'last name': 'Jetson', 'age': 110 };
//   var querystring = EncodeQueryData(data);
// 
function EncodeQueryData(data)
{
   var ret = [];
   for (var d in data)
      ret.push(encodeURIComponent(d) + "=" + encodeURIComponent(data[d]));
   return ret.join("&");
}

edited May 23 '17 at 12:34

Community

1
1

answered May 22 '13 at 09:57

SimonSimCity

6,415
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You should be able to drop the first encodeURIComponent I should think, unless the field names have non-ascii chars – mplungjan May 22 '13 at 12:17

score 2 · Answer 3 · answered May 22 '13 at 09:51

2

after for loop you can do like: string = string.slice(0,-1)

answered May 22 '13 at 09:51

Grijesh Chauhan

57,103
20
141
208

Or `string += "&"+subkey + "="+ obj[key][subkey];` and at the end `... string.substring(1)` – mplungjan May 22 '13 at 09:53
1

@Christoph sorry I commented correct but answered wrong, for mplungjan let me think – Grijesh Chauhan May 22 '13 at 09:55
@mplungjan sorry :( I didn't understand, `string.substring(1)` will remove first `char` if I am not wrong, please example bit more I am also new learner web-languages .. – Grijesh Chauhan May 22 '13 at 10:00
Yes it will, and I moved the & to the start. – mplungjan May 22 '13 at 12:15

letiagoalves · Answer 4 · 2013-05-22T09:56:25.023

1

For each iterarion append first & except for the first one.

var obj = { a: {b:1, c:3 }, d :{f:5}}
var string = "";
for(var key in obj){
   for(var subkey in obj[key]){
      if(string !== "") string += "&";
      string += subkey + "=" + obj[key][subkey];
    }
}

edited May 22 '13 at 09:56

answered May 22 '13 at 09:50

letiagoalves

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4
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Finding last iteration in for in loop javascript

4 Answers4