Javascript chained scope and context

Question

Is it possible to define a function run that acts like this?

    a = run('var x = 100;')
    b = run('console.log(x);') // prints 100
    c = run('y = 1;')
    d = run('console.log(y);') // prints 1

I tried several ways, using apply and passing the same context, binding a context to a function, returning a closure with a recursive call etc. but I can't seem to get anything to work.

Seems like this is masking a more fundamental problem. Why do you need this? — Andrew Li, Jul 01 '17 at 16:40
I want to make a Javascript "interpreter" in a page, in its own separate context and scope. — user1194032, Jul 02 '17 at 05:58

pacificpelican · Answer 1 · 2017-07-01T16:44:25.710

1

Yeah, as MyLibrary says, you probably want eval, if you really want to do this. So:

var run = eval;
a = run('var x = 100;')
b = run('console.log(x);') // prints 100
c = run('y = 1;')
d = run('console.log(y);') // prints 1

would seem to work.

JavaScript allows assigning functions to variables, so you can set the run variable to eval. As far as eval, you may want to learn about it and as you can see from comments, its use in normal function creation is often discouraged.

edited Jul 01 '17 at 16:44

answered Jul 01 '17 at 16:41

pacificpelican

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Please don't encourage to use `eval`. – PeterMader Jul 01 '17 at 16:41
If I use eval it's going to be run in the window context. I'd like to use my own context and save the changes that eval makes to it. – user1194032 Jul 02 '17 at 05:57

score 0 · Answer 2 · answered Jul 01 '17 at 16:39

0

Are you referring to eval function?

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval

answered Jul 01 '17 at 16:39

MyLibary

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Javascript chained scope and context

2 Answers2