Automatically console.log the name and value of all variables in a script

Question

I often find one of the most repetitive tasks when writing JavaScript is the need to constantly check the value of variables, especially as a script grows more complex.

Is there a way to automatically log the variable values to the console via calling a function?

e.g.

var foo = 1,
    bar = true,
    yin = ['item 1', 'item 2'],
    yang = 'a string',
    tan = $(this);

function() {
    yang = 'another string';
}

foo += 1;

yin.push('item 3');

function logMyVariables();

would log:

foo: 2
bar: true
yin: item1, item2, item 3
yang: another string
tan: [object Object]

What do you mean "automatically"? Like ever x number of seconds it logs? — user5797159
– user5797159, Commented May 22, 2016 at 0:03
You could store all variables in an object in the outermost scope, or make it global, and simply log that object to the console when you need to see your variables, for example: demo. — David Thomas
– David Thomas, Commented May 22, 2016 at 0:09
@DavidThomas, I'm after something that can traverse the script and log every variable it finds sequentially. This includes Global and Local variables, as they are encountered in the script. I don't think manually declaring them in an object would work, as this relies on already knowing their value. — Timmah
– Timmah, Commented May 22, 2016 at 0:38

Julien Grégoire · Accepted Answer · 2016-05-22 02:57:09Z

1

You can call debugger;. This will pause your script and give you a snapshot at that point of many things, including all variables, local and global.

Try to run the snippet below with your dev tools opened, you'll see the result. This works in Chrome and Firefox at least.

function init() {
  var foo = 1,
    bar = true,
    yin = ['item 1', 'item 2'],
    yang = 'a string',
    tan = this;

  (function(){
    yang = 'another string';
    
  }());

  foo += 1;

  yin.push('item 3');

  debugger;

}

init();

answered May 22, 2016 at 2:57

Julien Grégoire

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