Difference Between Number() and parseInt() in Converting Strings?

Number(): Searches the entire string for numbers. If it finds anything else, it will return NaN (short for Not a Number).

parseInt() / parseFloat(): Returns the first number in the string, ignoring the rest. If there are no numbers at the beginning of the string, it will return NaN.

let's take an example:

Example 1:
let a = "1hola1";
console.log(Number(a));
console.log(parseInt(a));
output->
NaN
1

Example 2:
let a = "1";
console.log(Number(a));
console.log(parseInt(a));
output->
1
1


In conclusion , We use Number() for the Strings that only contains numbers,the parseInt() does the opposite.

Comments

[Sunny]

You can use parseInt() on decimal values and it will return the floor of that number.
for eg:

parseInt(4.5)
output: 4

Number(4.5)
output: 4.5

[yns]

For Sure ! You can also use the Math functions such as ( Math.floor() , Math.ceil() , etc...) to achieve that .

[sachin kotian]

why cant they just return 0? unpredictable

[Endrit Shabani]

because how would you know if it returned 0 because it got "0" or because it had an invalid string?

[Hassan Tahir]

welcome to javascript? :p

[sachin kotian]

been years now out of this shit moving to java

[Mackson Isani]

Number() for the win then!

[Chuks Gabriel]

What if you pre-pend + to the variable? For example:

let a = +"1hola1";

What is executed under the hood for the type casting?`

parseInt() / parseFloat()
Or
Number()