how to find if a number is float or integer?
1.25 --> float
1 --> integer
0 --> integer
0.25 --> integer
views:
145answers:
4
+1
A:
Try this.
function isFloat (n) {
return n===+n && n!==(n|0);
}
function isInteger (n) {
return n===+n && n===(n|0);
}
no
2010-10-07 20:59:07
only works if a number is passed
John Hartsock
2010-10-07 21:11:51
heh awesom exploit, it's pretty much mine (`n===+n` to check for numeric, `n|0` to round), but with built-in operators. funky
Claudiu
2010-10-07 21:11:57
@John Hartsock a string is never going to be a numeric value. It's a string. The point of this function is to test whether a value is a Javascript numeric value that has no fractional part and is within the size limits of what can be represented as an exact integer. If you want to check a string to see if it contains a sequence of characters that represent a number, you'd call `parseFloat()` first.
Pointy
2010-10-07 21:23:15
@Pointy but parseFloat("1.1a") will still return 1.1. Suppose you had a text field you wanted to validate that it was an float and only a float without alpha characters. Testing weather a text field from an input element for decimal(float)
John Hartsock
2010-10-07 21:28:07
@John Hartsock: it won't return true unless a number primitive was passed. I think that makes sense given the names of the functions. Anything else should be a candidate for isString, isBoolean, etc. if such functions are being written.
no
2010-10-08 02:43:30
A:
As others mentioned, you only have doubles in JS. So how do you define a number being an integer? Just check if the rounded number is equal to itself:
function isInteger(f) {
return typeof(f)==="number" && Math.round(f) == f;
}
function isFloat(f) { return typeof(f)==="number" && !isInteger(f); }
Claudiu
2010-10-07 21:08:27
+1
A:
It really depends on what you want to achieve. If you want to "emulate" strongly typed languages then I suggest you not trying. As others mentioned all numbers have the same representation (the same type).
Using something like Claudiu provided:
isInteger( 1.0 ) -> true
which looks fine for common sense, but in something like C you would get false
galambalazs
2010-10-07 21:35:29
A:
check a remainder when dividing by 1:
function isInt(n){
return n%1==0
}
If you don't know that the argument is a number-
function isInt(n){
return typeof n== 'number' && n%1==0
}
kennebec
2010-10-07 21:43:03
Careful, this will also return true for an empty string, a string representing an integral number, `true`, `false`, `null`, an empty array, an array containing a single integral number, an array containing a string representing an integral number, and maybe more.
no
2010-10-08 16:53:45