Module Patterns

Hey, I was reading about: https://dev.to/tomekbuszewski/module-pattern-in-javascript-56jm Code snippet:

const Formatter = (function() {
  let timesRun = 0;

  const log = (message) => console.log(`[${Date.now()}] Logger: ${message}`);
  const setTimesRun = () => { 
    log("Setting times run");
    ++timesRun;
  }

  const makeUppercase = (text) => {
    log("Making uppercase");
    setTimesRun();
    return text.toUpperCase();
  };

  return {
    makeUppercase,
    timesRun,
  }
})();

const Formatter = (function() {
  let timesRun = 0;

  const log = (message) => console.log(`[${Date.now()}] Logger: ${message}`);
  const setTimesRun = () => { 
    log("Setting times run");
    ++timesRun;
  }

  const makeUppercase = (text) => {
    log("Making uppercase");
    setTimesRun();
    return text.toUpperCase();
  };

  return {
    makeUppercase,
    timesRun,
  }
})();

console.log(Formatter.makeUppercase("tomek"));
console.log(Formatter.timesRun);

console.log(Formatter.makeUppercase("tomek"));
console.log(Formatter.timesRun);

Why do we get timesRun zero, shouldn't it be 1? why is the public value different, im in a position to just "know" but cant explain this very well

8 Replies

13eck•3mo ago

Because timesRun is what’s called a primitive value, so when you’re returning your object it’s making a copy of the number 0. You want to, instead, include a function that returns the current value instead.

brrOP•3mo ago

oh its the pass by reference and value thing right?

13eck•3mo ago

Yep

brrOP•3mo ago

i see and why is it primitive 😃

13eck•3mo ago

https://developer.mozilla.org/en-US/docs/Glossary/Primitive

MDN Web Docs

Primitive - Glossary | MDN

In JavaScript, a primitive (primitive value, primitive data type) is data that is not an object and has no methods or properties. There are 7 primitive data types:

13eck•3mo ago

Because it’s not an object

brrOP•3mo ago

ok its int alright thank you

brrOP•3mo ago

Gaming

Programming

Module Patterns

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