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Rupesh Gupta
Rupesh Gupta

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There's more to console than .log() in JavaScript

While coding in JavaScript, I'm always perplexed on how JavaScript works. It's just as Kyle Simpson says -

"I don’t think anyone ever really knows JS, not completely anyway."

Any programmer who is learning JavaScript might have come across with this keyword for sure. So let's start with this. There's more to console than .log() in JavaScript.

The console object provides us with several different methods, like :

  1. log()
  2. error()
  3. warn()
  4. clear()
  5. time() and timeEnd()
  6. table()
  7. count()
  8. group() and groupEnd()
  9. custom console logs & list will go on in upcoming times.

1] console.log()
Mainly used to log(print) the output to the console. We can put any type inside the log(), be it a string, array, object, boolean etc.
// console.log() method


console.log([1, 2, 3, 4]); // array inside log
console.log({a:1, b:2, c:3}); // object inside log

2] console.error()

Used to log error message to the console. Useful in testing of code. By default the error message will be highlighted with red color.

// console.error() method  
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console.error('This is a simple error');

3] console.warn()
Used to log warning message to the console. By default the warning message will be highlighted with yellow color.
// console.warn() method

console.warn('This is a warning.');

4] console.clear()
Used to clear the console. The console will be cleared, in case of Chrome a simple overlayed text will be printed like : ‘Console was cleared’ while in firefox no message is returned.

// console.clear() method


5] console.time() and console.timeEnd()

Whenever we want to know the amount of time spend by a block or a function, we can make use of the time() and timeEnd() methods provided by the javascript console object. They take a label which must be same, and the code inside can be anything( function, object, simple console).

// console.time() and console.timeEnd() method

let fun = function(){
console.log('fun is running');
let fun2 = function(){
console.log('fun2 is running..');
fun(); // calling fun();
fun2(); // calling fun2();

In the above code sample, we can see that the label is ‘abc’ which is same for both the time() and the timeEnd() method. If we increase the amount of code inside the block defined by these methods, then the time will increase. It is also worth remembering that the time returned to the console will be in milliseconds and might be different each time we refresh the page.

6] console.table()
This method allows us to generate a table inside a console. The input must be an array or an object which will be shown as a table.

// console.table() method 
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console.table({'a':1, 'b':2});

7] console.count()
This method is used to count the number that the function hit by this counting method.
// console.count() method
for(let i=0;i<5;i++){

8] and console.groupEnd()
group() and groupEnd() methods of the console object allows us to group contents in a separate block, which will be indented. Just like the time() and the timeEnd() they also accepts label, again of same value.

// and console.groupEnd() method'simple');
console.error('error here');
console.log('vivi vini vici');
console.log('new section');

Top comments (1)

samuelcasey profile image

Very helpful to see all these in one place!