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javascriptarraysvariablesdynamic
MerC
MerC

Reputation: 323

How to dynamically create javascript variables from an array?

Lets say I have an array of names for a variable:

var varNames = new Array("name1","name2","name3");

How do I create var name1, var name2 and var name3 by just looping through the varNames array?

Upvotes: 9

Views: 24037

Answers (3)

KooiInc
KooiInc

Reputation: 123016

This will create global variables (in the global namespace, i.e. window).

var varNames = ["name1","name2","name3"];
for (var i=0;i<varNames.length;i+=1){
  window[varNames[i]] = 0;
}
name1; //=> 0

Since using global variables is considered bad practice, you could create variables within a custum object:

var myVariables = {}
   ,varNames = ["name1","name2","name3"];
for (var i=0;i<varNames.length;i+=1){
  myVariables[varNames[i]] = 0;
}
myVariables.name1; //=> 0

[ES20xx]

const myVariables = ['name1', 'name2', 'name3']
  .reduce( (a, v, i) => ({...a, [v]: i + 1 }), {});

console.log(JSON.stringify(myVariables, null, 2));

// to 'global' variables
Object.entries(myVariables).forEach( ([key, value]) =>
  window[key] = value );
  
console.log(`name1: ${name1}, name2: ${name2}`);

Upvotes: 14

Ilya Tsuryev
Ilya Tsuryev

Reputation: 2846

The direct answer to your question would be - you can do it using eval:

var varNames = new Array("name1","name2","name3");

for (var i=0; i<varNames.length; i++) {
    var varName = varNames[i];
    eval("var "+varName); // would be "var name1"
}

Please note though this is considered bad practice and usually there is no justification for using eval for such case. Also note that it's more common to create array using following style:

var varNames = ["name1", "name2", "name3"];

Upvotes: 2

Tom
Tom

Reputation: 4180

You can do it as follows. I added the alerts to prove you can set a value to those variables.

var varNames = new Array("name1","name2","name3");
for(var i = 0; i < varNames.length; i++) {
    window[varNames[i]] = i;
}
alert("name1: " + name1);
alert("name2: " + name2);
alert("name3: " + name3);

Upvotes: 2

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