JavaScript getter for all properties
Long story short: I'm in a situation where I'd like a PHP-style getter, but in JavaScript.
My JavaScript is running in Firefox only, so Mozilla specific JS is OK by me.
The only way I can find to make a JS getter requires specifying its name, but I'd like to define a getter for all possible names. I'm not sure if this is possible, but I'd very much like to know.
The closest you can find is __noSuchMethod__, which is JavaScript's equivalent of PHP's __call().
Unfortunately, there's no equivalent of __get/__set, which is a shame, because with them we could have implemented __noSuchMethod__, but I don't yet see a way to implement properties (as in C#) using __noSuchMethod__.
var foo = {
__noSuchMethod__ : function(id, args) {
alert(id);
alert(args);
}
};
foo.bar(1, 2);
Proxy can do it! I'm so happy this exists!! An answer is given here: Is there a javascript equivalent of python's __getattr__ method? . To rephrase in my own words:
var x = new Proxy({},{get(target,name) {
return "Its hilarious you think I have "+name
}})
console.log(x.hair) // logs: "Its hilarious you think I have hair"
Proxy for the win! Check out the MDN docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
Works in chrome, firefox, and node.js. Downsides: doesn't work in IE - freakin IE. Soon.
If you are coding in ES6 you can combine proxy and class to have a nice looking code like php :
class Magic {
constructor () {
return new Proxy(this, this);
}
get (target, prop) {
return this[prop] || 'MAGIC';
}
}
this binds to the handler, so you can use this instead of target.
Note: unlike PHP, proxy handles all the property request.
let magic = new Magic();
magic.foo = 'NOT MAGIC';
console.log(magic.foo); // NOT MAGIC
console.log(magic.bar); // MAGIC
You can check which browsers support proxy http://caniuse.com/#feat=proxy and class http://caniuse.com/#feat=es6-class. Node 8 support both.
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