JS: Map Filter

Here's a function that filters map object.

const xah_map_filter = ((map_obj, f) => {
    /* [
Returns a new map where f(key,value) returns true.

http://xahlee.info/js/js_map_filter.html
Version 2018-04-13
] */
    const result = new Map();
    for (let [k,v] of map_obj) { if ( f(k,v) ) { result.set(k,v); }};
    return result;
}
);

// test
const m = new Map([ [3, "n3"], [4, "n4"]]);

console.log (
    xah_map_filter(m, ((k,v) => ( ( v === "n4" ) ? true : false )))
);