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Javascript Array reduceRight() Method
Description:
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.
Syntax:
array.reduceRight(callback[, initialValue]);
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Here is the detail of parameters:
Return Value:
Returns the reduceRightd single value of the array.
Compatibility:
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;
};
}
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Example:
<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>
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This will produce following result:
To understand it in better way you can Try it yourself.
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