JavaScript abs

Return the absolute value of the number

function abs (mixed_number)  {
    // Return the absolute value of the number  
    // 
    // version: 909.322
    // discuss at: http://phpjs.org/functions/abs    // +   original by: Waldo Malqui Silva
    // +   improved by: Karol Kowalski
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Jonas Raoni Soares Silva (http://www.jsfromhell.com)
    // *     example 1: abs(4.2);    // *     returns 1: 4.2
    // *     example 2: abs(-4.2);
    // *     returns 2: 4.2
    // *     example 3: abs(-5);
    // *     returns 3: 5    // *     example 4: abs('_argos');
    // *     returns 4: 0
    return Math.abs(mixed_number) || 0;
}

external links: original PHP docs | raw js source

Examples

» Example 1

Running

abs(4.2);

Should return

4.2

» Example 2

Running

1	abs(-4.2);

Should return

4.2

Dependencies

No dependencies, you can use this function standalone.

Open syntax issues

php.js uses JsLint to help us keep our code consistent and prevent some common bugs.

Eventually we want all code to pass or at least take into consideration most fixes suggested by JsLint, following this JsLint configuration we’ve decided on.

Authors

Thanks to the following developers, you get to have abs goodness in JavaScript.

Waldo Malqui Silva ( original )
Karol Kowalski ( improved )
Kevin van Zonneveld ( improved )
Jonas Raoni Soares Silva ( improved )

Comments

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Use:

[CODE]
your_stuff('here');
[/CODE]

for proper code formatting
By submitting code here you are allowing us to use it in php.js hence dual licensing it under the MIT and GPL licenses

Kevin van Zonneveld
4 Sep '09

@ Jay: "Later" has arrived. We're now on GitHub!
http://github.com/kvz/phpjs

Some more info about the change here:
http://kevin.vanzonneveld.net/techblog/article/svn_to_git/

Kevin van Zonneveld
22 Mar '09

@ Jay: I'm working on 1 github project and a.t.m. I do not find the speed satisfying. I imagine all that SSH traffic causes quite some load but git pull times of > 60 seconds are just not acceptable. Maybe later though! Thanks

Jay
6 Mar '09

You should really consider putting this project up on GitHub.com, it would be a perfect fit. That way people could modify and improve the code, and then send you a pull request for you to merge their changes. It's a very nice way to develop open source projects.

Kevin van Zonneveld
15 Jan '09

@ Paul: It was actually an issue in the exit function. Should be fixed now, thanks for letting us know!

Paul
15 Jan '09

I downloaded php.namespaced.*.js at 2009-01-14 15:28 HST. There appears to be a space missing which is causing javascript errors. Search string "functionPropagation". I was able to resolve the error in php.namespaced.js and php.namespaced.min.js, but not php.namespaced.packed.js due to the packing operation.

BTW: This package is incredible!

Kevin van Zonneveld
12 Jan '09

@ Nile: Hey Nile thanks for your contribution. Unfortunately there are a couple of issues with it:
- depends on an outside function: applyEncode
- does not support associative arrays (in terms of traversing)
- does not support index arrays, numbers, etc (in terms of encoding)

Please have a look here:
http://www.json.org/json2.js

The code is public domain, so maybe it's possible to modify it and use it in PHP.JS. We could look into that!

Nile
9 Jan '09

json_encode

var arr = new Array('Hello');
var applyEncode = function(varIn){
return '{'+varIn+'}';
}
var json_encode = function(value){   var data = '';
   for(i=0,endCount='';i&lt;value.length;++i){
   var endCount = (i!=value.length-1) ? &quot;, &quot; : &quot;&quot;;
   data += '&quot;'+key(value[i])+'&quot; : &quot;'+value[key(value)]+'&quot;'+endCount;
   }   return applyEncode(data);
}
document.write(json_encode(arr));

Reena
8 Sep '08

Good

Kevin van Zonneveld
13 Apr '08

@ Jonas Raoni: Thanks I'll update the function.
@ Philip: I'll update your name!

Philip
12 Apr '08

Hey, just fyi... Philip and Philip Peterson are both me ;-)

Jonas Raoni
12 Apr '08

A shorter version of this would be:

return Math.abs (n) || 0;

Kevin van Zonneveld
2 Apr '08

Philip: Good idea, I'll add it, thanks!

Philip
31 Mar '08

Dunno where this belongs, but how about this code for echo()?

function echo()
{
  for(i=0;i&lt;echo.arguments.length;i++)
  {
    if(document.body &amp;&amp; document.body.innerHTML) {document.body.innerHTML=document.body.innerHTML+echo.arguments[i];
} else {
document.write(echo.arguments[i]);
}
  }}

Kevin van Zonneveld
31 Jan '08

@ _argos: Nice work! Added!

_argos
31 Jan '08

Hi Kevin I'm here again look this ports.

if ( defined ( 'CONSTANTE' ) ) {
 
    console.log ( CONSTANTE );
 
} 
function defined ( constant_name ) {
 
        return ( ( window [ constant_name ] !== undefined ) ? true : false );
 }
 
 
 
// ----- 
// [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
 
console.log ( range ( 0, 12 ) );
  
 
// [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100]
 
console.log ( range( 0, 100, 10 ) ); 
 
 
// ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'];
 console.log ( range( 'a', 'i' ) );
 
 
 
// ['c', 'b', 'a']; 
console.log ( range ('c', 'a' ) );
 
 
 function range ( low, high, step ) {
 
        var matrix = [];
 
        var inival, endval, plus; 
        var walker = step || 1;
 
        var chars  = false;
         
 
        if ( !isNaN ( low ) &amp;&amp; !isNaN ( high ) ) {
 
                inival = low; 
                endval = high;          
 
        } else if ( isNaN ( low ) &amp;&amp; isNaN ( high ) ) {
                 chars = true;
 
                inival = low.charCodeAt ( 0 );
 
                endval = high.charCodeAt ( 0 ); 
        } else {
 
                inival = ( isNaN ( low ) ? 0 : low );
                 endval = ( isNaN ( high ) ? 0 : high );
 
        }
 
         
        plus = ( ( inival &gt; endval ) ? false : true );
 
        
         if ( plus ) {
 
                while ( inival &lt;= endval ) {
 
                        matrix.push ( ( ( chars ) ? String.fromCharCode ( inival ) : inival ) ); 
                        inival += walker;
 
                }
         } else {
 
                while ( inival &gt;= endval ) {
 
                        matrix.push ( ( ( chars ) ? String.fromCharCode ( inival ) : inival ) ); 
                        inival -= walker;
 
                }
         }
 
                
 
        return matrix; 
}
 
 
 // -----
 
console.log ( strcmp ( 'waldo', 'Waldo' ) );
 
console.log ( strcmp ( 'Waldo', 'waldo' ) ); 
console.log ( strcmp ( 'waldo', 'waldo' ) );
 
 
 function strcmp ( str1, str2 ) {
 
        var size1 = str1.charCodeAt ( 0 );
 
        var size2 = str2.charCodeAt ( 0 ); 
        
 
        return ( ( size1 == size2 ) ? 0 : ( ( size1 &gt; size2 ) ? 1 : -1 ) );
 }

_argos
30 Jan '08

@Karol Kowalski : Hi, thanks for take the time to check my port, I make the same tests like you, because I think that native functions always are more slower, so ever I use self hacks :p again thanxs for your time.

PS: Sorry for my badly English, but i have 4 years without use it :p

Kevin van Zonneveld
30 Jan '08

@ Karol Kowalski: Awesome work Karol! I've updated the function. Thanks for putting in the extra effort. Greatly appreciated!

Karol Kowalski
30 Jan '08

I run a test and it appeared that my function with Math.abs was around 40% more time consuming than yours. I tried to optimize it and ended up with 20% gain, and the code is still smaller and more readable. I tested it in Firefox, IE7, Safari and Opera with similar results. To see what's causing the overhead I run a function that would just return Math.abs, withoud checking for validity, still it was 10% slower than your function. It seems that Math.abs API is always slower than what can be accomplished with JS hack, a bit sad.

Still, for code readability I would sugget using the code of abs_math2.

Here's the test code:

if (!window['console']) {
 
console={}
console.log=alert
} 
var start;
 
function abs_math2 ( mixed_number ) {
  return ( ( isNaN ( mixed_number ) ) ? 0 : Math.abs ( mixed_number ) );}
 
function abs_math( mixed_number )  {
  var abs=Math.abs( mixed_number );
  return ( !isNaN ( abs ) ) ? abs : 0}
 
function abs_cond( mixed_number )  {
  return ( ( !isNaN ( mixed_number ) ) ? ( ( mixed_number &lt; 0 ) ? ( mixed_number * -1 ) : mixed_number ) : 0 );
} 
 
start=new Date();
 
for (var i=100000;i;i--) { 
abs_cond(4.2);
abs_cond(-4.2);
abs_cond(-5);
abs_cond('_argos');abs_cond(-Infinity);
 
}
 
console.log((new Date())-start) 
 
start=new Date();
 
for (var i=100000;i;i--) { 
abs_math(4.2);
abs_math(-4.2);
abs_math(-5);
abs_math('_argos');abs_math(-Infinity);
 
}
 
console.log((new Date())-start) 
 
start=new Date();
 
for (var i=100000;i;i--) { 
abs_math2(4.2);
abs_math2(-4.2);
abs_math2(-5);
abs_math2('_argos');abs_math2(-Infinity);
 
}
 
console.log((new Date())-start) 
 
//my results
//Firefox 2.0.11
//1000//1422
//1219

Kevin van Zonneveld
30 Jan '08

@ Karol Kowalski: Using native Javascript for this is probably best so I've updated the function. But I'm not totally certain that this is faster. Doesn't the Math libary have to be loaded or something? Can somebod shed a light on this?

For reference, this was the original by _argos:

function abs( mixed_number )  {
    // +   original by: _argos
    return ( ( !isNaN ( mixed_number ) ) ? ( ( mixed_number &lt; 0 ) ? ( mixed_number * -1 ) : mixed_number ) : 0 );
}

Karol Kowalski
30 Jan '08

Why not use native JS Math.abs for this. I believe this should be faster than conditional expressions.

function abs( mixed_number )  {
    // http://kevin.vanzonneveld.net
    // +   original by: _argos
    // *     example 1: abs(4.2);
    // *     returns 1: 4.2    // *     example 2: abs(-4.2);
    // *     returns 2: 4.2
    // *     example 3: abs(-5);
    // *     returns 3: 5
    // *     example 4: abs('_argos');    // *     returns 4: 0
 
        var abs=Math.abs( mixed_number )
        return ( !isNaN ( abs) ) ? abs : 0
}

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