JavaScript getter for all properties

user_91238 0
Viewed 37879

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.

getter firefox javascript
9 Answers

The closest you can find is __noSuchMethod__ (__noSuchMethod__ is deprecated), 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);
Ionut_G_Stan_588080

Javascript 1.5 does have getter/setter syntactic sugar. It's explained very well by John Resig here

It's not generic enough for web use, but certainly Firefox has them (also Rhino, if you ever want to use it on the server side).

Javier_116490

If you're looking for something like PHP's __get() function, I don't think Javascript provides any such construct.

The best I can think of doing is looping through the object's non-function members and then creating a corresponding "getXYZ()" function for each.

In dodgy pseudo-ish code:

for (o in this) {
    if (this.hasOwnProperty(o)) {
        this['get_' + o] = function() {
            // return this.o -- but you'll need to create a closure to
            // keep the correct reference to "o"
        };
    }
}
nickf_90210

This is not exactly an answer to the original question, however this and this questions are closed and redirect here, so here I am. I hope I can help some other JS newbie that lands here as I did.

Coming from Python, what I was looking for was an equivalent of obj.__getattr__(key)and obj.__hasattr__(key) methods. What I ended up using is: obj[key] for getattr and obj.hasOwnProperty(key) for hasattr (doc).

user_81630530

It is possible to get a similar result simply by wrapping the object in a getter function:

const getProp = (key) => {
  const dictionary = {
    firstName: 'John',
    lastName: 'Doe',
    age: 42,
    DEFAULT: 'there is no prop like this'
  }
  return (typeof dictionary[key] === 'undefined' ? dictionary.DEFAULT : dictionary[key]);
}

console.log(getProp('age')) // 42

console.log(getProp('Hello World')) // 'there is no prop like this'

user_82522670
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