CFLib.org – Common Function Library Project

arrayReduce(array, callback)

Last updated July 31, 2013

author

Adam Cameron

Version: 1 | Requires: CF9 | Library: CFMLLib

Description:
Similar to Javascript's one ref https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce

Return Values:
The result of the reduction. Can be any data type

Example:

function add(required numeric currentValue, required numeric index, required array array, numeric previousValue){
	return previousValue + currentValue;
}


result = arrayReduce([1,2,3,4], add, 0);

writeDump([result]);

Parameters:

Name Description Required
array Array to reduce Yes
callback Callback function to use to reduce. Will receive the following arguments: element (of current iteration of the all), index, array, (optional) result (of preceeding call to callback()) Yes

Full UDF Source:

/**
 * CFML implementation of Array.reduce()
 * v1.0 by Adam Cameron with assistance from Adam Tuttle and Russ Spivey
 * 
 * @param array 	 Array to reduce (Required)
 * @param callback 	 Callback function to use to reduce. Will receive the following arguments: element (of current iteration of the all), index, array, (optional) result (of preceeding call to callback()) (Required)
 * @return The result of the reduction. Can be any data type 
 * @author Adam Cameron (dac.cfml@gmail.com) 
 * @version 1.0, July 31, 2013 
 */
public any function arrayReduce(required array array, required any callback, any initialValue){
    var startIdx = 1;
    if (!structKeyExists(arguments, "initialValue")){
        if (arrayLen(array) > 0){
            var result = callback(array[1], 1, array);
            startIdx = 2;
        }else{
            return;
        }
    }else{
        var result = initialValue;
    }
    for (var i=startIdx; i <= arrayLen(array); i++){
        result = callback(array[i], i, array, result);
    }
    return result;
}
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