Nodejs Array Sort sortAscending()

Method Source Code

/* Write a function that finds the largest possible product of any three numbers
 * from an array./*www .  ja v  a 2 s  .c  o m*/
 *
 * Example:
 * largestProductOfThree([2, 1, 3, 7]) === 42
 *
 * Extra credit: Make your function handle negative numbers.
 */

// Create a convenience function that sorts arrays ascending numerically
Array.prototype.sortAscending = function() {
  this.sort(function(a, b) {
    return a - b;
  });
  return this;
};

var largestProductOfThree = function(array) {

  // Make a copy of the input array and sort it numerically
  array = array.slice().sortAscending();

  var secondFromLast = array[array.length - 2];
  var thirdFromLast = array[array.length - 3];

  return array[array.length - 1] * Math.max(secondFromLast * thirdFromLast, array[0] * array[1]);
};

Related

1. sort(fn)

   Array.prototype.sort = function(fn) {
     if (!arguments[0]) {
       fn = function(a, b) {
         return a.compareTo(b);
       };
     for (var i = 0, len = this.length; i < len - 1; i++) {
       for (var j = i + 1, len = this.length; j < len; j++) {
         if (fn(this[i], this[j]) > 0) {
   ...
   

2. sortABC( property )

   Array.prototype.sortABC = function( property )
     return this.sort( function( a,b)
       var links = a[property].replace(/?, "Oe").replace(/?, "Ae").replace(/?,"Ue");
       var rechts = b[property].replace(/?, "Oe").replace(/?, "Ae").replace(/?,"Ue");
       if( links < rechts) return -1;
       if( links > rechts) return 1;
       return 0;
   ...
   

3. sortAscending()

   Array.prototype.sortAscending = function() {
     return this.sort( function( a, b ) {
       if ( a > b ) {
         return 1;
       return a < b ? -1 : 0;
     } );
   };
   

4. sortBool(iteratee)

   Array.prototype.sortBool = function(iteratee) {
       var _iteratee = function(a, b) {return iteratee(a, b) ? -1 : 1};
       return this.sort(_iteratee);
   };
   

5. sortBy( field, ascending_order )

   Array.prototype.sortBy= function( field, ascending_order ) {
     var asc = ascending_order ? 1 : -1;
     return this.sort(function (a, b) {
            return (asc *(a[field] <= b[field]) ? -1:1);
     });
   };
   

6. sortBy(()

   Array.prototype.sortBy = (function() { 
       function identity(v){return v;} 
       function ignoreCase(v){return typeof(v)==="string" ? v.toLowerCase() : v;} 
       function makeCompareFunction(f, opt){ 
           opt = typeof(opt)==="number" ? {direction:opt} : opt||{}; 
           if(typeof(f)!="function"){ 
               var prop = f; 
               f = function(v1){return !!v1[prop] ? v1[prop] : "";} 
           if(f.length === 1) { 
               var uf = f; 
               var preprocess = opt.ignoreCase?ignoreCase:identity; 
               f = function(v1,v2) {return preprocess(uf(v1)) < preprocess(uf(v2)) ? -1 : preprocess(uf(v1)) > preprocess(uf(v2)) ? 1 : 0;} 
           if(opt.direction === -1) return function(v1,v2){return -f(v1,v2)}; 
           return f; 
       return function(callbacks){ 
           var array = this; 
           function tb(func, opt) { 
               var x = typeof(this) == "function" ? this : false; 
               var y = makeCompareFunction(func, opt); 
               var f = x ? function(a, b) { 
                               return x(a,b) || y(a,b); 
                         : y; 
               f.thenBy = tb; 
               f.sort = () => array.sort(f); 
               return f; 
           return tb(callbacks); 
       }; 
   })();
   

7. sortBy()

   Array.prototype.sortBy = function() {
         function _sortByAttr(attr) {
             var sortOrder = 1;
             if (attr[0] == "-") {
                 sortOrder = -1;
                 attr = attr.substr(1);
             return function(a, b) {
                 var result = (a[attr] < b[attr]) ? -1 : (a[attr] > b[attr]) ? 1 : 0;
   ...