I want to do something like this:
function delegate(func, params) {
func(params);
}
function foo(a, b) {
// do stuff
}
function bar(x, y, z) {
// do stuff
}
delegate(foo, 1, 2);
delegate(bar, 1, 2, 3);
I know delegate() will not do what I want as written. How can I write a delegate() that would work for the above examples?
I'll throw my hat into the ring with an ES6 flavored example. I'm also using bind as opposed to call or apply in order to delay the function invocation.
function delegate(fn, ...args) {
if (args.length !== fn.length) {
console.log(`Warning, function ${fn.name} takes ${fn.length} arguments.`);
return;
}
return fn.bind(null, args);
}
function foo(a, b) {
console.log('foo invoked');
}
function bar(a, b, c) {
console.log('bar invoked');
}
var whoops = delegate(foo, 1, 2, 3); // => 'Warning, function foo takes 2 arguments.'
var myFn1 = delegate(foo, 1, 2);
var myFn2 = delegate(bar, 1, 2, 3);
myFn1(); // => 'foo invoked'
myFn2(); // => 'bar invoked'
[].slice.call(arguments, 1); just asks for it. ...args just looks so much better!In case you're still having trouble you can create the function like this:
function delegate(func) {
var args = Array.prototype.slice.call(arguments, 1);
return func.apply(null, args);
}
That should do what you're looking for.
// Examples
function sum(x, y) {
return x + y;
}
function sumThree(x, y, z) {
return x + y + z;
}
delegate(sum, 4, 5);
//=> 9
delegate(sumThree, 1, 2, 3);
//=> 6
arguments.