How can I make console.log show the current state of an object?

Solution 1:

I think you're looking for console.dir().

console.log() doesn't do what you want because it prints a reference to the object, and by the time you pop it open, it's changed. console.dir prints a directory of the properties in the object at the time you call it.

The JSON idea below is a good one; you could even go on to parse the JSON string and get a browsable object like what .dir() would give you:

console.log(JSON.parse(JSON.stringify(obj)));

Solution 2:

What I usually do if I want to see it's state at the time it was logged is I just convert it to a JSON string.

console.log(JSON.stringify(a));

Solution 3:

Vanilla JS:

@evan's answer seems best here. Just (ab)use JSON.parse/stringify to effectively make a copy of the object.

console.log(JSON.parse(JSON.stringify(test)));

JQuery specific solution:

You can create a snapshot of an object at a certain point in time with jQuery.extend

console.log($.extend({}, test));

What is actually happening here is jQuery is creating a new object with the test object's content, and logging that (so it will not change).

AngularJS (1) specific solution:

Angular provides a copy function that can be used to the same effect: angular.copy

console.log(angular.copy(test));

Vanilla JS wrapper function:

Here is an function which wraps console.log but will make a copy of any objects before logging them out.

I wrote this in response to a few similar but less robust functions in the answers. It supports multiple arguments, and will not try to copy things if they are not regular objects.

function consoleLogWithObjectCopy () {
  var args = [].slice.call(arguments);
  var argsWithObjectCopies = args.map(copyIfRegularObject)
  return console.log.apply(console, argsWithObjectCopies)
}

function copyIfRegularObject (o) {
  const isRegularObject = typeof o === 'object' && !(o instanceof RegExp)
  return isRegularObject ? copyObject(o) : o
}

function copyObject (o) {
  return JSON.parse(JSON.stringify(o))
}

example usage: consoleLogWithObjectCopy('obj', {foo: 'bar'}, 1, /abc/, {a: 1})

Solution 4:

That > Object in the console, isn't only showing the current state. It actually is deferring reading the object and it's properties until you expand it.

For example,

var test = {a: true}
console.log(test);
setTimeout(function () {
    test.a = false; 
    console.log(test);
}, 4000);

Then expand the first call, it will be correct, if you do it before the second console.log returns

Solution 5:

using Xeon06's hint, you may parse his JSON in an object, and here is the log function I now use to dump my objects :

function odump(o){
   console.log($.parseJSON(JSON.stringify(o)));
}