Compare two floats in JavaScript

Question

How can I compare two floats in JavaScript? Or perhaps a float and an int.

if (5 > 4.3.3)

if (5.0 > 5.3)

Thankful for all input!

Update

I need to for an iPhone app that I am developing in Appcelerator. I need to compare iOS versions and display different content to each. So if a device is running 5.0 and another is running 4.3.3 I need to know the difference in my code.

Answer 1

Just like that.

if (5.0 > 5.3)

In your 1st example you do not have a valid number [ 4.3.3 ].

Answer 2

You may use something along the lines of http://maymay.net/blog/2008/06/15/ridiculously-simple-javascript-version-string-to-object-parser/

Basically he uses:

function parseVersionString (str) {
    if (typeof(str) != 'string') { return false; }
    var x = str.split('.');
    // parse from string or default to 0 if can't parse
    var maj = parseInt(x[0]) || 0;
    var min = parseInt(x[1]) || 0;
    var pat = parseInt(x[2]) || 0;
    return {
        major: maj,
        minor: min,
        patch: pat
    }
}

Answer 3

Basic comparator can look like:

  1. Convert to correct positional structure
  2. Compare lengths
  3. Compare values

 function compareVer(a, b, sep = '.') { // 1. Convert to correct positional structure const aP = a.split(sep); const bP = b.split(sep); // 2. Compare lengths if (aP.length > bP) return 1; if (bP.length > aP) return -1; for (let i = 0; i < aP.length; ++i) { // 3. Compare values // You can add necessary type conversions // Ex.: add parseInt, if you want to support `001=1` and not `3f=3f` if (aP[i] > bP[i]) return 1; if (bP[i] > aP[i]) return -1; } return 0; } console.log(compareVer('5', '4.3.3')); // 1 gt console.log(compareVer('5.0.2', '5.0.2')); // 0 eq console.log(compareVer('5.0', '5.3')); // -1 lt