javascript reflection: get variables

Question

how can be a collection of global and/or local varibles be obtained in javascript?

(like e.g. in Python by globals() or locals())

if there is no such functionality available in javascript, how do some javascript console interfaces obtain them, to be able to autocomplete?

here i have found pretty similar question: stackoverflow.com/questions/3831932/access-all-local-variables — mykhal
– mykhal, Commented Aug 3, 2011 at 19:50

SLaks · Accepted Answer · 2010-07-05 14:50:04Z

4

You're looking for the for / in loop.

To get all globals:

for(var name in this) {
    var value = this[name];
    //Do things
}

(This will only work correctly when run in global scope; you can wrap it in an anonymous function to ensure that. However, beware of with blocks)

To get all properties of a particular object:

for(var name in obj) {
    //Optionally:
    if (!obj.hasOwnProperty(name)) continue;    //Skip inherited properties

    var value = obj[name];
    //Do things
}

However, there is no way to loop through all local variables.

edited Jul 5, 2010 at 14:50

answered Jul 5, 2010 at 14:02

SLaks

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9 Comments

mykhal Over a year ago

well, this is an object in(tro)spection, not exactly what i am asking for. but definitely useful for browser environment reflection.

SLaks Over a year ago

Then what are you asking for?

mykhal Over a year ago

SLaks: you note that it's not possible would be sufficient, if it's the case (it was not already there in time of writing my previuos comment)

mykhal Over a year ago

SLaks: .. my answer was meant rather on pure javascript, where is no window object. but your answer this is useful for browser env, thanks :)

SLaks Over a year ago

If there is no window, you can use this in global scope.

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