Convert string to number

Given a string, convert the string to a number, using JavaScript.

Solution

To convert given string str into a number using JavaScript, call Number() constructor and pass the string as argument to the method.

Number(str)

If the string is a valid number, then the constructor returns a number created from the given string.

Programs

1. Given a string str. Convert the string to number.

var str = '5421';
var n = Number(str);
console.log(n);

Since the string is a valid number, Number() returns a number.

2. Given a string str. This string does contain some alphabets. Check programmatically if this string can convert into a number.

var str = '5421ab';
var n = Number(str);
console.log(n);

Since the given string is not a valid number, Number() returns NaN.