How to convert a string (with leading zero or not) to an integer?

Question

How to convert a string (with leading zero or not) to an integer? For example, '08' to 8.

score 18 · Accepted Answer · edited May 23 '17 at 11:45

18

There are several ways to convert a string to a number, I prefer to use the unary + operator:

var number = +"08"; // 8

This is the equivalent of writing:

var number = Number("08"); // 8

Unlike parseInt(), when using + or Number() no radix is necessary because the internal number conversion will not parse octal numbers. If you want the parseInt() or parseFloat() methods, it's also pretty simple:

var number = parseInt("08", 10); // 8

parseInt and parseFloat are less reliable for user input because an invalid numeric literal might be considered salvageable by these functions and return an unexpected result. Consider the following:

parseInt("1,000");   // -> 1, not 1000
+"1,000";            // -> NaN, easier to detect when there's a problem

Extra Reading

edited May 23 '17 at 11:45

Community

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answered Feb 08 '11 at 13:54

Andy E

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what about 010 number not an string ? parseInt(), Number, +, didn't work – Umair Ahmed Jan 10 '17 at 13:04
@Umair: `010` is already a number. In "loose mode" or older browsers, the number will be 8. In strict mode, a syntax error will be thrown (but you can use `0o10` if you *transpile* with Babel or use newer browsers exclusively) – Andy E Jan 12 '17 at 08:56
yes your are right it's already number i wanna get decimal value of this number or remove leading 0 how can i do – Umair Ahmed Jan 12 '17 at 10:40
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@Umair: that seems really odd. You can basically convert the number back into an octal string, then parse it correctly. `+(010.toString(8))`, for instance. – Andy E Jan 12 '17 at 12:09

score 6 · Answer 2 · answered Feb 08 '11 at 13:50

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Use parseInt() with the radix argument. This disables autodetection of the base (leading 0 -> octal, leading 0x -> hex):

var number = parseInt('08', 10);
// number is now 8

answered Feb 08 '11 at 13:50

ThiefMaster

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the radix argument is the one i always forget sometimes. +1 – KJYe.Name Feb 08 '11 at 13:59

score 3 · Answer 3 · answered Feb 08 '11 at 13:50

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you can use parseInt(); with base 10 or parseFloat(); to parse float

answered Feb 08 '11 at 13:50

KJYe.Name

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score 2 · Answer 4 · answered Feb 08 '11 at 13:50

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Use the parseInt function. Reference: link

answered Feb 08 '11 at 13:50

Cassie Dee

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How to convert a string (with leading zero or not) to an integer?

4 Answers4