Need lexical context in eval for Javascript

Question

I am writing a string parser that takes input like "{x} + 20" and evaluates the lexical value of x with the sum of 20 and returns. So

var x = 10;
var new = eval("{x} + 20".replace("/\{(\w+\}/g", "$1"));

and here "new" should equal 30.

How can this be done?

justin.m.chase · Accepted Answer · 2010-09-17 18:56:38Z

1

I believe you just do this:

var x = 10
var y = eval("x + 20")

No?

answered Sep 17, 2010 at 18:56

justin.m.chase

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2 Comments

PS "new" is a reserved keyword so if you're getting errors it could be related to that.

Also he is feeding replace a string instead of a RegExp object, and even then the regex is invalid (missing a ')')