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JavaScript-30-Day-9

KUMAR HARSH
The best way to learn is to teach. Programmer by Passion and Developer for Fun, and I love sharing my journey with everyone.
Updated on ・4 min read

Developer Tools and Console Tricks

demo

ss

On Day-9 of JavaScript-30 we learned a lot of handy console tricks and dev tools to increase our productivity in Web Development.

Lessons Learned:

-Suppose we want to know what is causing a particular thing to happen on a site, you know it's javascript making it happen but not sure exactly which line is responsible.

There is a handy dev tool for us:

Just open the console -> find the element in DOM on which the change is happening -> right click on it -> go to break on -> select attribute modifications

attribute

Next time when you click on the element, it's going to pop a debugger command in. It's a break point for us and it will pause exactly at the line of code that is causing the attribute.
(remove the break point from the same place).

Now we'll see some handy console tricks:

Regular

console.log("Hello");
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This is our regular console.log() which simply outputs on the console.

regular

Interpolated

console.log("Hello I am a %s string", "💩");
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interpolation

It interpolates whatever we have passed into the second one into our first message.

Styled

console.log("%c I am some great text", "font-size:20px;background:red;");
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styled

We can style our text with %c and apply any font-css.

warning!

console.warn("OH NOOOO!");
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warning

It displays a warning on the console as well as the stack trace as to where the warning came from.

Error:

console.error("Oh Shit!");
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error

It displays a error message in the console along with the stack trace as to where it was generated.

Info

console.info("Crocodiles eat 3-4 people per year");
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info

In firefox it displays with a small 'i' icon.

Testing

console.assert(1 === 2, "That is Wrong!");
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assert

Assert is fired only if something is false. So using assert we can test for something and if it is false it will throw an error.

clearing

console.clear();
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clear

It clears everything on the console.

Viewing DOM Elements

const p = document.querySelector("p");
console.log(p);
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Using console.log(p) actual element is displayed.

p

console.dir(p);
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But using console.dir(p) displays all the properties and methods associated with that element.

dir

Grouping together

const dogs = [
  { name: "Snickers", age: 2 },
  { name: "hugo", age: 8 },
];

dogs.forEach((dog) => {
  console.groupCollapsed(`${dog.name}`);
  console.log(`This is ${dog.name}`);
  console.log(`${dog.name} is ${dog.age} years old`);
  console.log(`${dog.name} is ${dog.age * 7} dog years old`);
});
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This is how the normal output is like:
without collapse

Now using grouping

dogs.forEach((dog) => {
  //console.group(`${dog.name}`);
  console.groupCollapsed(`${dog.name}`);
  console.log(`This is ${dog.name}`);
  console.log(`${dog.name} is ${dog.age} years old`);
  console.log(`${dog.name} is ${dog.age * 7} dog years old`);
  console.groupEnd(`${dog.name}`);
});
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We can either use console.group() or console.groupCollapsed(), the collapsed displays output where the output groups are collapsed by default.

grouped

counting

console.count("Harsh");
console.count("Harsh");
console.count("Harsh");
console.count("Harsh");
console.count("Harsh");
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counts

It counts how many times we have used a specific word, or number, or object , or DOM node etc.

timing

console.time("fetching data");
fetch("https://api.github.com/users/cenacrharsh")
  .then((data) => data.json())
  .then((data) => {
    console.timeEnd("fetching data");
    console.log(data);
  });
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!timing](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/q3tz6gy97yiy1rmtcnq4.png)

If we want to track how long a particular task takes we can start a timer.

table

console.table(dogs);
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It displays an array object in the form of a table.

table

and with this our project for the day was completed.

GitHub repo:

Blog on Day-8 of javascript30

Blog on Day-7 of javascript30

Blog on Day-6 of javascript30

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You can also do the challenge at javascript30

Thanks @wesbos , WesBos to share this with us! 😊💖

Please comment and let me know your views

Thank You!

Discussion (8)

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rash123 profile image
RASHMI VERMA

Great👍

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cenacr007_harsh profile image
KUMAR HARSH Author

Thanks.

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kritebh profile image
Kritebh Lagan Bibhakar

Kudos for consistency 👏

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cenacr007_harsh profile image
KUMAR HARSH Author

Thanks.

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ROHIT KUMAR • Edited

Awesome👌👌👌

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cenacr007_harsh profile image
KUMAR HARSH Author

Thanks.

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someshium

Thanks for letting us know the challenge. Nice blog 👍

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cenacr007_harsh profile image
KUMAR HARSH Author

Glad you liked it.