JavaScript - 以字符串的形式将十进制数转换为 4 位二进制数

Question

I wrote a Javascript method that will take a decimal number input and gives a binary number in the form of string.

Example 1: Input: 15 Output : "1111"

The method I wrote works as follows:

If my input number is 15 ,

var t = parseInt(15,10).toString(2);

then output of t will be "1111"

My question is how to convert a number lesser than 15 also as a 4-bit binary number string. As in,

Input: 4

Desired output : "0100" , but what I get right now is, "100" .

Please help me with the workaround.

Answer 1

Use padStart

The padStart() method pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start of the current string.

 var t1 = parseInt(4, 10).toString(2).padStart(4, "0") var t2 = parseInt(15, 10).toString(2).padStart(4, "0") console.log(t1) console.log(t2)