How do you convert a string to a number in JavaScript?
TL;DR
In JavaScript, you can convert a string to a number using several methods. The most common ones are Number()
, parseInt()
, parseFloat()
, and the unary plus operator (+
). For example, Number("123")
converts the string "123"
to the number 123
, and parseInt("123.45")
converts the string "123.45"
to the integer 123
.
How do you convert a string to a number in JavaScript?
Using the Number()
function
The Number()
function converts a string to a number. It can handle both integer and floating-point numbers.
let str = '123';let num = Number(str); // 123let floatStr = '123.45';let floatNum = Number(floatStr); // 123.45
Using the parseInt()
function
The parseInt()
function parses a string and returns an integer. It can also take a second argument, the radix (base) of the numeral system to be used.
let str = '123';let num = parseInt(str); // 123let floatStr = '123.45';let floatNum = parseInt(floatStr); // 123let binaryStr = '1010';let binaryNum = parseInt(binaryStr, 2); // 10
Using the parseFloat()
function
The parseFloat()
function parses a string and returns a floating-point number.
let floatStr = '123.45';let floatNum = parseFloat(floatStr); // 123.45
Using the unary plus operator (+
)
The unary plus operator can be used to convert a string to a number. It is a shorthand method and works for both integers and floating-point numbers.
let str = '123';let num = +str; // 123let floatStr = '123.45';let floatNum = +floatStr; // 123.45
Handling non-numeric strings
If the string cannot be converted to a number, these methods will return NaN
(Not-a-Number).
let invalidStr = 'abc';let num = Number(invalidStr); // NaNlet intNum = parseInt(invalidStr); // NaNlet floatNum = parseFloat(invalidStr); // NaNlet unaryNum = +invalidStr; // NaN