This question already has answers here:
Prefix zero changes output in number addition [duplicate]
(2 answers)
Closed 9 years ago.
I have encountered a very weird issue with my JavaScript program. I have fount that JavaScript for some reason changes 040000 into 16384! [Example] Does anyone know why JavaScript is doing this?
It's because in js, number literals prepended with 0 are considered octal (base 8)
For example
010 == 8
In your example 040000 is really 4*8*8*8*8 = 16384 because in octal each 0 in the right multiplies the value by 8.
EDIT: Bonus:
If the leading 0 is in a string representation, (for example, if it was introduced by the user), and you want to avoid converting to octal, specify the base (aka radix) with value 10 in the parseInt method call, like this
var number = parseInt("040000", 10); //number will be 40000 ;)
In recent browsers, the radix is 10 by default, but not in old browsers, so if you want maximum compatibility also, always specify the radix parameter (usually 10).
Cheers
Because javascript thinks its in OCTAL format
Explanation:-
Javascript (like most programming languages) allows us to work directly with both octal and hexadecimal numbers, all we need is a way to tell which number base we are using when we specify a number. To identify octal and hexadecimal numbers we add something to the front of numbers using those bases to indicate which base we are using. A leading 0 on the front of a number indicates that the number following is octal while a leading 0x indicates a hexadecimal number. The decimal number 18 can therefore also be represented as 022 (in octal) and 0x12 (in hexadecimal). We don't put a special symbol on the front of decimal numbers so any number that doesn't start with 0 or 0x is assumed to be decimal.
So its same in your case
040000(base8)=16384(base10)
Related
This question already has answers here:
Number with leading zero in JavaScript
(3 answers)
Closed 3 years ago.
I guess I can format it back. I'm just interested in why it's happening.
function test(d){
console.log(d) // 151028224
}
console.log(test(00001100101000))
By default, any number literally written with a zero at the beginning is considered as octal (base 8) number representation, and then, when you show back any number with console.log, it is written as its base 10 representation.
console.log(05)
console.log(06)
console.log(07)
console.log(010)
console.log(011)
It's recommended to avoid this in code, because it can lead to confusions :
if the number contains the digits 8 or 9, it cannot be a base-8 number, and thus treated as base 10 !
console.log(05)
console.log(06)
console.log(07)
console.log(08) // Yiiik !
console.log(09) // Yiiik !
console.log(010)
console.log(011)
The function has nothing to do with it.
The JavaScript compiler converts your number literal into a Number when it compiles the source code.
Since the number starts with a 0, it is treated as octal instead of decimal.
I have a array like this.
var elements=[5614,6619,7220,7320,7830,8220,0111,0112,0113,0142,0149]
Am converting every element to string so as to use with jquery autocomplete.
Am using .map function to do this.
elements = elements.map(String);
output is
["5614", "6619", "7220", "7320", "7830", "8220", "73", "74", "75", "98", "149"]
Function is taking 0111,0112,0113,0142 all these values as Octal values and converting them to decimal.
I don't want this conversation and want to preserve leading Zero also , How can I do this , please help.
Function is taking 0111,0112,0113,0142 all these values as Octal values and converting them to decimal.
It's not the function doing that, it's this:
var elements=[5614,6619,7220,7320,7830,8220,0111,0112,0113,0142,0149]
In loose mode, if you start a number with a 0 followed by a series of octal digits, it's octal. That's why 010 === 8 is true:
console.log(010 === 8); // true
And heaven help us, but if you have a 0 followed by a number with non-octal decimal digits (8 or 9), it's decimal, which is why 011 === 09 and 9 === 09 are true:
console.log(011 === 09); // true
console.log(9 === 09); // true
The solution is:
Use strict mode ("use strict";). Both legacy octal literals (010) and legacy non-octal decimal literals (08) are disallowed in strict mode. (If you need to write octal, you can, with the newer 0o10 format — that's the number eight.)
Don't write leading zeros on numbers (with the possible exception of a 0 just prior to a . in a fractional number less than one)
You can't fix elements after the fact (because it's impossible to know, once they're numbers, which ones were incorrectly written in octal), you have to fix it at the point you're creating it, e.g.:
var elements=[5614,6619,7220,7320,7830,220,111,112,113,142,149]
I receive a long XML from backend. To further use the xml I convert it to JSON object using one of the standard XMLtoJSON javascript library. The issue is, some of the XML value contains number with leading zeros eg: 001072.
The problem is, when javascript library converts xml to JSON, number with leading zeros give completely different value.
For example
“001072” converts “570”
Other times it parse it correctly. For example:
“0045678” converts to 45678
The problem is how javascript handle number with zeros. I don’t know the reason of this strange behavior!!
Please suggest a solution which can parse number with zeros consistently and how can I use it with xmltojson library
This is most likely a problem with octal literals. If a number starts with a leading 0, JavaScript by default will try to parse it as an octal literal.
For this reason, you should always specify the radix parameter when calling parseInt. The library probably does not do that.
parseInt("012", 8); // 10
parseInt("012", 10); // 12
I think this is the offending line in the library, probably. Either edit the library, or edit your XML.
Octal numbers with the leading zero are on the way out. For ECMAScript5 they can still cause problems and are thus not allowed in strict mode and throw a runtime error. You really should not be using 3rd party scripts that are not in strict mode they are dangerous for way too many reasons, as you can see with the handling of the octal numbers.
As ECMAScript 6 becomes more wide spread the use of the leading zero will be pushed out all together.
Octals literals will have a '0o' prefix 0o10 === 8 can be uppercase 'o' but I am sure you can see this will be a hassle. ES6 will also formalise the binary format with the prefix 0b1000 === 8 though most browsers have supported it for some time. Hex has also been around for a while 0x08 == 8
The reason some numbers with leading zeros are decmil and some octal is dependent on what digits are in the number. Octal does not use the digits 8 and 9 so any number that have these digits can not be octal.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Workarounds for JavaScript parseInt octal bug
Parsing a string using parseInt method returns invalid output .
Code :
parseInt("08");
Excepted Output :
8
Real Output :
0
Code [This returns output correctly] :
parseInt("8")
Output :
8
Why it happens ?
You need to specify the base:
parseInt("08",10); //=>8
Otherwise JavaScript doesn't know if you are in decimal, hexadecimal or binary.
(This is a best practise you should always use if you use parseInt.)
Also see Number:
Number("08"); // => 8
What is the difference between parseInt() and Number()?
What is the difference between parseInt(string) and Number(string) in JavaScript?
You should tell parseInt its 10 based:
parseInt("08", 10);
JavaScript parseInt() Function
If the radix parameter is omitted, JavaScript assumes the following:
If the string begins with "0x", the radix is 16 (hexadecimal)
If the string begins with "0", the radix is 8 (octal). This feature is
deprecated If the string begins with any other value, the radix is 10
(decimal)
http://jsfiddle.net/YChK5/
Strings with a leading zero are often interpreted as octal values. Since octal means, that only numbers from 0-7 have a meaning, "08" is converted to "0". Specify the base to fix this problem:
parseInt("08", 10); // base 10
As usual, the MDN is a good source of information:
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt#Octal_Interpretations_with_No_Radix
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Workarounds for JavaScript parseInt octal bug
EXTREMELY confused here.
parseInt("09") = 0
but
parseInt("9") = 9
Why is the prefixed zero not just stripped out?
alert(parseInt("01")); = 1
.. rage quit
Because that is treated as octal format, by default. If you want to get 9, you must add number base you want, and thats 10, not 8 (for octal), so call:
parseInt("09", 10);
A.7. parseInt
parseInt is a function that converts a string into an integer. It stops when it sees a nondigit, so
parseInt("16") and parseInt("16 tons") produce the same result. It would be nice if the
function somehow informed us about the extra text, but it doesn't.
If the first character of the string is 0, then the string is evaluated in base 8 instead of base 10. In base 8, 8 and
9 are not digits, so parseInt("08") and parseInt("09") produce 0 as their result. This error causes
problems in programs that parse dates and times. Fortunately, parseInt can take a radix parameter, so that
parseInt("08", 10) produces 8. I recommend that you always provide the radix parameter.
"JavaScript: The Good Parts by Douglas Crockford. Copyright 2008 Yahoo! Inc.,
978-0-596-51774-8."
this the reasons:
If the string begins with "0x", the radix is 16 (hexadecimal)
If the string begins with "0", the radix is 8 (octal). This feature is deprecated
If the string begins with any other value, the radix is 10 (decimal)
http://www.w3schools.com/jsref/jsref_parseInt.asp
Do
parseInt("09", 10)
To specify base 10.
Edit: To clarify, a number prefixed by a zero will be assumed to be of octal notation, and "09" isn't a valid octal number.