How can I convert a string to a variable name in Node.js? [duplicate]

Question

//Admin.js

var insertAdminFeed = function(s, id, timestamp){
    var admin_att_new_key = '12345';
    var admin_att_new_key2 = 'abc';
    var admin_att_new_key3 = 'zyzyz';

    var s = 'admin_att_new_key';
    console.log(global[s]); //should print '12345'
};
exports.insertAdminFeed = insertAdminFeed;

I want to convert a string to a variable in node.js (I have many keys, and I don't want to write if/else statements for all of them) How can I do that?

You can't. This will be possible in ES6 (with symbols) very nicely but in ES5 unless you use a parser you have no way to access a variable's name from itself. You also can not iterate over all closure variables. What you should do is probably var admin= {key:'12345',key2:'abc',key3:'zyzyzy'} and then use Object.keys(admin) to iterate through those keys when you need them. — Benjamin Gruenbaum
– Benjamin Gruenbaum, Commented Jan 9, 2014 at 0:34
Node.js modules aren't run in the global scope like JavaScript in a browser, vars also scope to functions, and admin_att_new_key{,2,3} seems rather like the start of an Array. — Jonathan Lonowski
– Jonathan Lonowski, Commented Jan 9, 2014 at 0:34

Simon Boudrias · Accepted Answer · 2014-01-09 00:36:30Z

10

This is not really possible in JavaScript.

You'd usually use an object literal to achieve similar needs.

var key = 'foo';
obj[key] = 1;
obj['foo'];

To be thorough, it is technically possible in JS using eval. But really, don't do this.

eval("var "+ name + " = 'some value';");
eval("console.log("+ name  +")");

answered Jan 9, 2014 at 0:36

Simon Boudrias

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1 Comment

Aaron Dufour Over a year ago

I agree that its a bad idea, but eval(s) (assuming s defined as in the question) would work - no need for the variable to also be declared in an eval.

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