javascript - Reduce with higher-order callback parameter -

i have tried many ways parent parameter visible reduce's callback function must missing something...

// static var y = [0, 1, 2, 3, 4, 5, 6, 7].reduce(     function(arr, x){         arr.push(math.pow(2, x));         return arr},[]); console.log(y);  // dynamic var lambda = function(arr, func) {     return (function(f) { return arr.reduce(function(a, x) {         a.push(f(x));         return a;     }, [])})(func); } var y = lambda([0, 1, 2, 3, 4, 5, 6, 7],function(x){return math.pow(x);}); console.log(y); 

output:

[1, 2, 4, 8, 16, 32, 64, 128]   [nan, nan, nan, nan, nan, nan, nan, nan]  

demo @ jsfiddle

you missing 1 of parameters math.pow. might wanna invoke lambda this

var y = lambda([0, 1, 2, 3, 4, 5, 6, 7], function(x) {     return math.pow(2, x); }); 

also, don't have complicate lambda construction iife. can simply

var lambda = function(arr, func) {     return arr.reduce(function(a, x) {         a.push(func(x));         return a;     }, []); } 

edit: suggested in comments can use array.prototype.map, this

console.log(arr.map(function(x) {     return math.pow(2, x); }));