# .css-df1pn7{display:block;width:16rem;}     # Learn all about Numbers in JavaScript

SURYA L
·Jun 21, 2022·

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• Converting numbers
• Parsing Numbers
• Math Object
• Rounding Integers
• Numeric Separators
• Conclusion

Hello everyone, hope you are all doing well. My name is Surya L, and the aim of this blog is to teach you all about Numbers in JavaScript

As a primitive data type, numbers in JavaScript can store both integers and floats. It is really helpful to know how numbers behave in JavaScript and how to use them correctly.

## Converting numbers

To convert a string that contains only a number (eg: "2800") to a Number type we use a wrapper object called Number

``````Number("2800")

// returns 2800 as Number data type
``````

or we could also use "+" for converting, as JavaScript sees the + it will do type coercion and convert the operands to numbers

``````+"2800"

// returns 2800 as Number data type
``````

## Parsing Numbers

• Number.parseInt(): parseInt is used to parse the Integer out of the string they may even contain characters but the string should start with a number
``````Number.parseInt("2.4rem") ;

// returns 2

Number.parseInt("2rem") ;

// returns 2

Number.parseInt("rem2") ;

// returns NaN
``````
• Number.parseFloat(): parseFloat is used to parse the Floating point number out of the string they may even contain characters but the string should start with a number.
``````Number.parseFloat("2.4rem") ;

// returns 2.4

Number.parseFloat("2rem") ;

// returns 2

Number.parseFloat("rem2") ;

// returns NaN
``````
• Number.isNan(): As we saw above that Number.parseFloat("rem2") gives us NaN
``````Number.parseFloat("rem2") ==NaN
// returns false
``````

But this returns false so to check if the number is NaN we use isNaN()

``````Number.isNaN(Number.parseFloat("rem2"));
// returns true
``````
• Number.isFinite(): It is used to check if a number is finite and this method doesn't do type coercion, It is used to check if the value is a number.
``````Number.isFinite("28")

// returns false

Number.isFinite(28)

// returns true

Number.isFinite(28/0)

// returns false
``````

## Math Object

• Math is a built-in object that has properties and methods for mathematical constants and functions.

Some properties:

• Math.E: Euler's constant and the base of natural logarithms; approximately 2.718.

• Math.LN10: Natural logarithm of 10; approximately 2.303.

• Math.PI: The ratio of a circle's circumference to its diameter; approximately 3.14159.

Some Methods:

• Math.max(): This returns the maximum element out of the given elements.
``````const randomNums=[2,5,1,4,8,3];

console.log(Math.max(...randomNums));

// returns 8
``````
• Math.min(): This returns the minimum element out of the given elements.
``````const randomNums=[2,5,1,4,8,3];

console.log(Math.min(...randomNums));

// returns 1
``````

## Rounding Integers

• Math.trunc(): It removes the decimal part of the number.
``````const a=4.7;

console.log(Math.trunc(a));

// returns 4
``````
• Math.round(): It rounds the number to the nearest integer.
``````const a=4.7;

console.log(Math.round(a));

// returns 5
``````
• Math.ceil(): It rounds the number to the next largest integer.
``````const a=4.7;

console.log(Math.ceil(a));

// returns 5
``````
• Math.floor(): It rounds down the number to the closest integer.
``````const a=4.7;

console.log(Math.floor(a));

// returns 4
``````

As you might see and say that Math.floor() and Math.trunc() returns the same value

but when dealing with negative numbers the output will be different, let's look at an example

``````const a=-4.7;

console.log(Math.trunc(a));

//returns -4

console.log(Math.floor(a));

//returns -5
``````

As the Math.trunc() removes the decimal part which leaves us with -4 and Math.floor() which rounds down the number which returns -5.

## Numeric Separators

• We could make use of underscores ( _ ) for seeing large numbers clearly.

Example:

``````const a=280_500_000_000;

console.log(a)

//280500000000
``````

JavaScript ignores the underscores, but you cannot use the underscores at the beginning of the number or right after the decimal point.

## Conclusion

• Number("56") is the syntax used to convert a string to Number.

• parseInt is used to parse the Integer out of the string they may even contain characters but the string should start with a number.

• Math is a built-in object that has properties and methods for mathematical constants and functions.

• We could make use of underscores ( _ ) for seeing large numbers clearly.

• We can use Math functions to round off the number.

Thanks for reading the blog. Do let me know what you think about it.

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