Insert a value of a key in other value

Question

I have a list:

var lt = {
  "part1" : "p1",
  "part2" : "p2",
  . (another key/value)
  . (another key/value)
  . (another key/value)
  . (another key/value)
}

and a variable

var myVar = "part2";

I want if myVar equal to the lt I want the variable z take the value p2 of lt. I have this:

for (var i = 0; i < lt.length; i++) {
    if (myVar === lt[i]) {
      z = lt.[i]
    }
}

However when I test it chrome console the var lt return undifined

[http://jsfiddle.net/55fmggL9/](http://jsfiddle.net/55fmggL9/) this is how you should do it — Amit.rk3, Aug 06 '15 at 12:07

Below the Radar · Accepted Answer · 2015-08-06T12:34:44.187

2

A dict is not an array. lt.length would returns undefined.

First test if lt[myVar] exists and then copy the value into z:

var lt = {
   "part1" : "p1",
   "part2" : "p2",
   "part3" : "p3"
}

var myVar = "part2";
var z;

if(typeof lt[myVar] !== "undefined"){
   z = lt[myVar];
}

console.log(z)
---> "p2"

or simply:

if(myVar in lt){
  z = lt[myVar];
}

see: http://jsfiddle.net/55fmggL9/4/

edited Aug 06 '15 at 12:34

answered Aug 06 '15 at 12:02

Below the Radar

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2

You can check variable directly without loop: `lt[myVar] == undefined` or `if('part2' in lt)` – Max Lipsky Aug 06 '15 at 12:09
@Max Lipsky I tought myVar was a value, not a key, I'll edit – Below the Radar Aug 06 '15 at 12:12

overburn · Answer 2 · 2015-08-06T12:53:01.450

1

for (var i in lt) {
    if (myVar === i) {
      z = lt[i]
    }
}

edited Aug 06 '15 at 12:53

answered Aug 06 '15 at 12:02

overburn

1,194
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Insert a value of a key in other value

2 Answers2