var foo = function(a, b, c) {
console.log(a);
console.log(b);
console.log(c.id);
};
//this works obviously
foo("a man", "b man", {id: "c.id man"});
var par = {
a: "a val",
b: "b cal",
c: {
id: "c.id val"
}
};
//can I make this work automatically?
foo(par);
Question is in code sample.
Can I automatically "unwrap" the par object to use the properties to fill in the function parameters?
Is there some kind of foo(par.unwrap()) in javascript?
You can, but given that object properties are unordered it's a little hacky. The solution is to parse the function as a string to get the name of the parameters.
Here's a utility function :
function callunwrap(f,o){
f.apply(null, (f.toString().match(/\([^\)]*\)/)[0].match(/\w+/g)||[]).map(function(name){
return o[name];
}));
}
Usage example
var foo = function(a, b, c) {
console.log(a);
console.log(b);
console.log(c.id);
};
var par = {
a: "a val",
b: "b cal",
c: {
id: "c.id val"
}
};
callunwrap(foo, par);
Now, as you see, callunwrap does a lot of things, I wouldn't recommend to use such a hacky thing in a real program. The usual non hacky solution is to have your function explicitly read the arguments :
var foo = function(o) {
console.log(o.a);
console.log(o.b);
console.log(o.c.id);
};
You can try
var parWorking = ["a val", "b cal", {
id: "c.id val"
}
];
foo.apply(this, parWorking);
JavaScript argument names can be arbitrary and irrelevant, so it doesn't attach too much importance to them. In other words, you cannot set specific arguments based on name. More important are their indexes.
If you create an array out of the object's values, you can use foo.apply() to pass them in:
foo.apply(null /* the context */, parAsArray);
Pretty easy to do it yourself?
var args = [];
for(var p in par){
args.push(par[p]);
}
console.log(args); // ["a val", "b cal", Object { id="c.id val"}]
foo.apply(this, args);
You can create upwrap() method for that Object.
var foo = function(a,b,c) {
console.log(a);
console.log(b);
console.log(c.id);
};
var par = {
a: "a val",
b: "b cal",
c: {
id: "c.id val"
},
unwrap:function(){
var valueArray=[];
for(key in this){
if(typeof this[key]!=="function"){
valueArray.push(this[key]);
}
}
return valueArray;
}
};
foo("a man", "b man", {id: "c.id man"});
foo.apply(null,par.unwrap())
You can do that if you use the ES-6 arguments deconstruction. The way to do it would be to define the function like
function foo({a, b, c}) {
//here just use a, b, c as you want;
}
var par = {
a: "a val",
b: "b cal",
c : {
id: "c.id val"
}
};
foo(par);
You can see the demo here
argumentsis dynamic.