javascript - Passing a math operator as a parameter -

i'd write function in javascript allows me pass in mathematical operator , list of ints , each item in list, apply operator it.

thinking of in terms of sum, i've come with:

function accumulate(list, operator){     var sum = 0;     each(var item in list){         sum = accumulator(sum, item);     }     print(sum); } 

testing code produces following error:

var list = new array(); list[0] = 1; list[1] = 2; list[2] = 3; 

js> accumulate(list, +); js: "<stdin>", line 9: syntax error js: accumulate(list, +); js: ..................^ js: "<stdin>", line 9: compilation produced 1 syntax errors. 

you can't pass operator parameter, can pass function:

function accumulate(list, accumulator){   // renamed parameter     var sum = 0;     for(var = 0; < list.length; i++){ // removed deprecated for…each loop         sum = accumulator(sum, list[i]);     }     print(sum); }  accumulate(list, function(a, b) { return + b; }); 

this pretty close array.prototype.reduce function does, though not exactly. mimic behavior of reduce, you'd have first element list , use seed accumulator, rather using 0:

function accumulate(list, accumulator, seed){     var = 0, len = list.length;     var acc = arguments.length > 2 ? seed : list[i++];     for(; < len; i++){         acc = accumulator(acc, list[i]);     }     print(acc); } 

this way, compute product of list (your method return 0):

accumulate(list, function(a, b) { return * b; });