Possible Duplicate:
Truncate leading zeros of a string in Javascript
What is the simplest and cross-browser compatible way to remove leading zeros from a number in Javascript ?
e.g. If I have a textbox value as 014 or 065, it should only return 14 or 65
We can use four methods for this conversion
10
const numString = "065";
//parseInt with radix=10
let number = parseInt(numString, 10);
console.log(number);
// Number constructor
number = Number(numString);
console.log(number);
// unary plus operator
number = +numString;
console.log(number);
// conversion using mathematical function (subtraction)
number = numString - 0;
console.log(number);
For the primitive type Number
, the safest max value is 253-1(Number.MAX_SAFE_INTEGER
).
console.log(Number.MAX_SAFE_INTEGER);
Now, lets consider the number string '099999999999999999999' and try to convert it using the above methods
const numString = '099999999999999999999';
let parsedNumber = parseInt(numString, 10);
console.log(`parseInt(radix=10) result: ${parsedNumber}`);
parsedNumber = Number(numString);
console.log(`Number conversion result: ${parsedNumber}`);
parsedNumber = +numString;
console.log(`Appending Unary plus operator result: ${parsedNumber}`);
parsedNumber = numString - 0;
console.log(`Subtracting zero conversion result: ${parsedNumber}`);
All results will be incorrect.
That's because, when converted, the numString value is greater than Number.MAX_SAFE_INTEGER
. i.e.,
99999999999999999999 > 9007199254740991
This means all operation performed with the assumption that the string
can be converted to number
type fails.
For numbers greater than 253, primitive BigInt
has been added recently. Check browser compatibility of BigInt
here.
The conversion code will be like this.
const numString = '099999999999999999999';
const number = BigInt(numString);
parseInt
?If radix is undefined or 0 (or absent), JavaScript assumes the following:
Exactly which radix is chosen is implementation-dependent. ECMAScript 5 specifies that 10 (decimal) is used, but not all browsers support this yet.
For this reason, always specify a radix when using parseInt