April 09, 2024

Training day 16 - JavaScript Basic to Beginners

Heloo people!!

Value Types: Number, String, Boolean, Symbol, Undefined, Null Reference Types: Objects, Functions, Arrays
Functions are Objects. Arrays are also Objects. Therefore Reference types have only Objects technically.
Primitives are copied by value. Objects are copied by their reference.

const circle = {
    radius: 1,
    draw() {
        console.log('draw');
    }
}

for (let key in circle) console.log(key, circle[key])

The above code is used to iterate over the properties in the object.

- ```
for(let key of circle)
    console.log(key)

The above code will give an error. To solve it we have circle.keys() method to iterate through the keys. This method returns key as string.

Another similar method we have Object.entries(). It returns key-value pairs as arrays.

    const circle = {
      radius: 1,
      draw() {
          console.log('draw');
      }
    };


    const another = {};

    for(let key in circle)
    another [key] = circle[key];

    //above for loop code is similar to the below one

    const another1 = Object.assign({}, circle);

If we want to add addition property to the properties we get from the circle object, it is like this:

const another = Object.assign({
color: 'yellow'
}, circle);

Yet another way to clone an object is as follows:


const another = {...circle};

This is called the spread operator.

Built-in objects: Math Object, String Object.
Template Literals to format strings in a better way.