CODEWITHSUNDEEP
node.jsvariablestracking
Deven Davies
Deven Davies

Reputation: 13

How can I see my node.js variables already initiated?

I'm pretty new to node.js and I was wondering: seeing as the scope of any variable created is set to a sort of global scope, is there any way of listing out what variable names have already been initiated?

Upvotes: 1

Views: 53

Answers (1)

jfriend00
jfriend00

Reputation: 707158

node.js variables are generally not global. The default is that any variable declared at the top level of a module is only in the module scope and does not conflict or interfere with any other modules.

Only variables explicitly assigned to the global object are actually available globally.

global.myVar = "foo";

All others are contained within a smaller scope - module scope or a function scope within a module.

So, if you have a module like this:

var x = 3;

module.exports = function() {
    return x;
}

Then, the variable x is not a global variable at all. It is contained with the scope of this module. It would not conflict with a variable in any other module of the same name.

Because top level variables in a module are actually local variables within a module function wrapper and Javascript does not provide any means of iterating the local variables within a function scope, there is no way to iterate all top level variables within a module scope.

If you wanted to be able to iterate all variables in some context, then you can use a different format and put them as properties on an object.

var obj = {};
obj.x = 3;
obj.y = 5;

// list all enumerable properties of obj
for (var prop in obj) {
    console.log("property: " + prop + " = ", + obj[prop]);
}

FYI, you can also use a debugger like node-inspector to view all variables declared within any given scope. You set a breakpoint in that scope and then look at the local variables present at that breakpoint.

Upvotes: 2

Related Questions