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Javascript array reduceRight() method applies a function simultaneously against two values of the array (from right-to-left) as to reduce it to a single value.
array.reduceRight(callback[, initialValue]); |
Here is the detail of parameters:
callback : Function to execute on each value in the array.
initialValue : Object to use as the first argument to the first call of the callback.
Returns the reduceRightd single value of the array.
This method is a JavaScript extension to the ECMA-262 standard; as such it may not be present in other implementations of the standard. To make it work you need to add following code at the top of your script:
if (!Array.prototype.reduceRight) { Array.prototype.reduceRight = function(fun /*, initial*/) { var len = this.length; if (typeof fun != "function") throw new TypeError(); // no value to return if no initial value, empty array if (len == 0 && arguments.length == 1) throw new TypeError(); var i = len - 1; if (arguments.length >= 2) { var rv = arguments[1]; } else { do { if (i in this) { rv = this[i--]; break; } // if array contains no values, no initial value to return if (--i < 0) throw new TypeError(); } while (true); } for (; i >= 0; i--) { if (i in this) rv = fun.call(null, rv, this[i], i, this); } return rv; }; } |
<html> <head> <title>JavaScript Array reduceRight Method</title> </head> <body> <script type="text/javascript"> if (!Array.prototype.reduceRight) { Array.prototype.reduceRight = function(fun /*, initial*/) { var len = this.length; if (typeof fun != "function") throw new TypeError(); // no value to return if no initial value, empty array if (len == 0 && arguments.length == 1) throw new TypeError(); var i = len - 1; if (arguments.length >= 2) { var rv = arguments[1]; } else { do { if (i in this) { rv = this[i--]; break; } // if array contains no values, no initial value to return if (--i < 0) throw new TypeError(); } while (true); } for (; i >= 0; i--) { if (i in this) rv = fun.call(null, rv, this[i], i, this); } return rv; }; } var total = [0, 1, 2, 3].reduceRight(function(a, b) { return a + b; }); document.write("total is : " + total ); </script> </body> </html> |
This will produce following result:
total is : 6 |
To understand it in better way you can Try it yourself.
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