JavaScript - pass string variable to eval

Question

Part of code my generates a string, which is then suppose to be used by a function to generated a chuck in VoxelJS.

An example string is "(y == 1)? 1 : 0"

Which I then need to be added to a function like this, eg. "function(x, y, z){return (y == 1)? 1 : 0}"

I thought using eval would change my string to the needed code, like this:

gtest = function(x, y, z){return eval(generationString) };

but I misunderstood how eval is used, and realized I needed to try something else.

If I look at gtest in the JavaScript console it says it's structure is function (x, y, z){return eval(generationString) } when I want it to look like function (x, y, z){return return (y == 1)? 1 : 0}}. Attempting to pass the code containting the eval causes VoxelJS to crash/freeze when it tries to generate new chunks.

How can I convert the string with the javascript code to code in a function in the way I want?

I realize this might be a hard to understand question, sorry about that, I'm not sure how to describe it any other way.

Your eval function should have worked, unless eval is not eval. Of course, it's potentially slow if that function is called very often. — Bergi
– Bergi, Commented Feb 25, 2016 at 2:56
@Bergi yeah it was being called hundreds of times a second, so it was probably just extremely slow — Keith M
– Keith M, Commented Mar 3, 2016 at 20:12

Community · Accepted Answer · 2017-05-23 11:50:30Z

1

I found the answer literally 30 seconds after posting this, use the function() constructor.

Given a string describing a Javascript function, convert it to a Javascript function

gtest = new Function('x', 'y', 'z', 'return ' + generationString);

edited May 23, 2017 at 11:50

CommunityBot

11 silver badge

answered Feb 25, 2016 at 2:28

Keith M

1,2492 gold badges19 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

JavaScript - pass string variable to eval

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related