Is it possible to have parameters for anonymous function?

Question

Given

var stuffs = [
    { id : 1, name : "orange"},
    { id : 2, name : "apple"}, 
    { id : 0, name:"grapes"}
];
var filterMethod1 = new function(o){return (o.id>=1);}; // this gives undefined error for o
function filterMethod2(o) {return (o.id>=1);};

Why is using anonymous function not working for array filter() method?

var temp = stuffs.filter(new function(o){ return (o.id>=1);}); // o is undefined if used this way

Using declared function works fine:

var temp = stuffs.filter(filterMethod2);

`new function(o) {...}` is trying to use the function as a constructor. — Barmar, Jun 19 '17 at 19:16

score 4 · Answer 1 · answered Jun 19 '17 at 19:19

You don't need to use new to create an anonymous function. The new keyword in Javascript is used to call a function as an object constructor, and the parameters are typically used by the constructor to initialize properties of the object. Just put the anonymous function in the argument to filter().:

var temp = stuffs.filter(function(o){ return (o.id>=1);});

score 2 · Answer 2 · answered Jun 19 '17 at 19:18

2

Just get rid of the "new" keyword and it should work.

answered Jun 19 '17 at 19:18

mikjay

36
3

A more complete answer would be to explain **why** removing the `new` keyword would solve the OP's issue. – mhodges Jun 19 '17 at 19:20
@Pointy Huh? `.filter()` is passing values to the function. – mhodges Jun 19 '17 at 19:22

Is it possible to have parameters for anonymous function?

2 Answers2