We recommend using regular expressions and the string
replace() method to remove leading zeros from a string.
let x = '0042'; x = x.replace(/^0+/, ''); x; // '42'; typeof x; // 'string'
Converting to a Number
You may have seen code that uses
x * 1 or
+x to remove leading zeros from a string.
This approach works for basic cases, with the key difference that you end up with a number rather than a string.
let x = '0042'; x = parseInt(x); x; // 42 typeof x; // 'number' let y = '007'; y = +y; y; // 7 typeof y; // 'number'
However, things get tricky with strings that contain hex, octal, and binary literals as shown below.
let x = '0xFF'; x = +x; x; // 255
Whether this behavior is correct depends on your use case.
However, if you want to treat
x as a string and remove leading zeros, the correct output here would be
In that case, using
parseInt() won't work.
You can tell
parseInt() to always use base 10 and avoid parsing strings that start with
0x as hexadecimal numbers, but then you end up with a
let x = '0xFF'; x = parseInt(x, 10); x; // 0, because `parseInt()` parses as much as it can typeof x; // 'number'
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