How do I get a set off a function call when a bool turns to true?

Question

I have a global variable that is only set to true when the user enters certain inputs, and I want to be able to have a function fire off. Some of these inputs are not via the handlers, so I can't use the JQuery change() function.

Any advice on how to workaround this problem?

More context is necessary here. What do have so far? What did you try? Why didn't what you tried work? — Alex Wayne, May 30 '13 at 01:17
There is no event to check if a variable changes, other than using an interval and repeatedly checking the variable, or doing what most people do, fire the function instead of changing the variable when the inputs change. — adeneo, May 30 '13 at 01:19

score 3 · Accepted Answer · answered May 30 '13 at 01:19

3

use a custom getter to do something else when the value changes:

myGlobal=true;


(function(){
  var shadow=myGlobal;
Object.defineProperty(
   window, 
   "myGlobal", 
   {
     get: function() {return shadow;}, 
     set: function(v){alert( 'myGlobal is now ' + v); return shadow=v;}
   }
);

}());

myGlobal=false;
myGlobal=true;

this works in old-ish IE and imposes less of a perf hit than Object.watch() and polyfills.

answered May 30 '13 at 01:19

dandavis

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By "oldish IE" you mean versions 8 and 9? – Bergi May 30 '13 at 01:42

score 0 · Answer 2 · edited May 23 '17 at 10:25

0

You can use the non-standard object.watch. Here is an implementation: https://gist.github.com/eligrey/384583

See Listening for variable changes in JavaScript or jQuery

edited May 23 '17 at 10:25

Community

1
1

answered May 30 '13 at 01:22

Fallexe

596
2
11

How do I get a set off a function call when a bool turns to true?

2 Answers2