Data types in javascript

There are two types of data types in javascript one is primitive and the other one is none-primitive

Primitive data types in javascript

Primitive data types are copied by value not by reference. Primitive data types are undefined, null, boolean, number, bigint, string, symbol. All other values are objects.we can’t change, add, or remove properties of primitive data types. primitives data types are immutable.

In primitive data types when we copy value of one variable to another variable then their values are transfer and when we change the value of one of them, the other one will not be effected.

1let x = 123;
2let y = x;
3console.log(x) // 123
4console.log(y) // 123

In this example we have copied x to y and then check their output. Both have same values (123). we have did example with integers but you can use strings, boolean and float data types.

1let x = 123;
2let y = x;
3x = 456;
4console.log(x) // 456 
5console.log(y) // 123

Here we have copied x to y and then changed the value of x to (456). When we log both, x value is 456 and y is 123. This is becuase x is copied by value not by reference.

None-Primitive data types in javascript

None Primitive data types are objects, arrays and regular Expressions.

In none-primitive data types when we copy one variable to another variable then their reference are transfer and when we change the value of one of them, then the other one's value will be change.

1let xArray = [1, 2, 3];
2let yArray = xArray;
3
4console.log("x array : " + xArray); // x array : 1,2,3
5console.log("y array : " + yArray); // y array : 1,2,3

In this example we have copied Array x to Array y and then check their output. Both have same values.

1 let xArray = [1, 2, 3];
2let yArray = xArray;
3
4yArray.push(4);
5console.log("x array : " + xArray);  // x array : 1,2,3,4
6console.log("y array : " + yArray); // y array : 1,2,3,4

Here we have created two arrays named xArray and yArray. Now have copied array x to array y. In line 4 we have pushed value '4' to array x. Now in output array is also changed. This is becuase array x is copied by reference not by value.

Conclusion

As we have studied in the start that primitive data types are coping by value and none primitive are coping by reference. By reference means when we change in one the other will be change.