Convert string literals in an array to variable name

Question

I'm new to javascript. I am trying to store object variable names in an array but the way I'm doing it, the array values become strings. Is there a way to change these values from strings to the object variable names? In the following code, the last statement is what I would like to use but it generates "undefined" because, I think, it's seen as a string. Thanks!

var plan1 = {
  name: "Lisa",
  price: 5.00,
  space: 100
}

var plan2 = {
  name: "John",
  price: 2.00,
  space: 150    

}

var myArray = [];

for (var i = 0; i < 2; i++) {
  myArray[i] = "plan" + (i + 1);
}

alert(plan2.name);
alert(myArray[1].name);

What you're trying to do doesn't sound well. Your application design is already broken if you have to do so. — zerkms
– zerkms, Commented Jun 30, 2014 at 22:26

Artem Volkhin · Accepted Answer · 2014-06-30 22:32:02Z

2

Disclaimer: it's a very bad style, try to avoid it. Look at http://nedbatchelder.com/blog/201112/keep_data_out_of_your_variable_names.html

You can consider using eval:

for (var i = 0; i < 2; i++) {
  myArray[i] = eval("plan" + (i + 1));
}

answered Jun 30, 2014 at 22:32

Artem Volkhin

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3 Comments

Quint Rahaman Over a year ago

Thank you! This works and I've read a few other comments that relay the same assessment you've made regarding its use. I still don't understand why it's considered, "...bad style." Nevertheless, for my initial use, this is meant to be used in a rough prototype. So far this bit of it is enough to continue building. Assuming the finished prototype passes muster, then professionals will take over. :-)

Artem Volkhin Over a year ago

It's a bad style because you consider all objects plan1, plan2, ... to be part of the same dataset. If it is so you better put them in single object: var plans = {1: {...smth...}, 2: {...smth else...}}. It's just harder to control all these separate variables. What if you need to copy all of them or do smth else? And eval is a bad practice too because you can easily add unnecessary complexity with it, just moving some logic inside eval call bit by bit.

Quint Rahaman Over a year ago

Thank you for your explanation and recommendation!

edtheprogrammerguy · Accepted Answer · 2014-06-30 22:27:38Z

1

You can't build the name like you are trying to do and get it to store the object with the same name. What you have in myArray is the strings "plan1" and "plan2". You would have to do something like myArray[0] = plan1; myArray[1] = plan2; Then it should work in the array like you want it to.

answered Jun 30, 2014 at 22:27

edtheprogrammerguy

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Comments

Bergi · Accepted Answer · 2014-06-30 22:31:20Z

0

Don't try to do that programmatically. Just build your array literal out of the parts that you want it to contain:

var plan1 = {
  name: "Lisa",
  price: 5.00,
  space: 100
};
var plan2 = {
  name: "John",
  price: 2.00,
  space: 150 
};
var myArray = [plan1, plan2];

Or even don't use those variables for the objects at all, and directly put them in the array structure:

var myArray = [{
  name: "Lisa",
  price: 5.00,
  space: 100
}, {
  name: "John",
  price: 2.00,
  space: 150    
}];

answered Jun 30, 2014 at 22:31

Bergi

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Comments

user3754372 · Accepted Answer · 2014-06-30 22:37:08Z

0

you can use

myArray[i] = window["plan" + (i + 1)];

working copy at http://plnkr.co/edit/7pY4Lcmx6wN1rQk9rklu?p=preview

answered Jun 30, 2014 at 22:37

user3754372

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4 Comments

zerkms Over a year ago

Why do you think plan1 is a global variable?

user3754372 Over a year ago

This is assuming they are global scope variables. will have to modify it accordingly if not. you may be better off doing something like this plnkr.co/edit/7pY4Lcmx6wN1rQk9rklu

user3754372 Over a year ago

i am sure it is in his case.

Artem Volkhin Over a year ago

Doesn't work for local variables. It can be done using eval for both global and local variables.

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