Call class instance as function (JS/TS)

Question

Let's say I have a logging class called Logger.

let log = new Logger(...);

Is it possible to specify a magic method in that class to be executed when the class instance is invoked as function? For example

log(...)

In php implementing the __invoke() magic method of a class achieves the same thing.

You can return a function from your Logger constructor, but it will be an arbitrary function not an instance (not inheriting from Logger.prototype) — Bergi
– Bergi, Commented Apr 13, 2016 at 12:05

Angelos Kyriakopoulos · Accepted Answer · 2016-04-13 12:23:18Z

3

function Logger() {
  return function log(arg1, arg2) {
    //@TODO: use the function's args
    // or the arguments property to
    // generate the log

    console.log(log.arguments);
  }
}
logger = new Logger();
logger('boom', 123, 'yolo');

This solution should to the trick you are looking for. How optimal it is or better ways of setting this up will probably be found in the comments below.

edited Apr 13, 2016 at 12:23

answered Apr 13, 2016 at 12:03

Angelos Kyriakopoulos

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2 Comments

Bergi Over a year ago

Please don't forget to include the drawbacks of this approach in your answer.

M-- Over a year ago

But this way Logger is not a class anymore, just a function.

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