Easy to forget memory leaks

easy-to-forget-memory-leaks.js

// Case 1: accidentally capturing an outer object in a lambda
class Foo {
  constructor(arr) {
    this.sayHellos = [];
    for (const languageData of arr) {
      this.sayHellos.push(() => {
        console.log(languageData.hello);   // oops, languageData is captured, even though it is not needed after this call 
      });
    };
  }
}

const arr = [{language: "English", hello: "Hello!"}, {language: "Chinese", hello: "Ni Hao!"}];
const foo = new Foo(arr);
for (const f of foo.sayHellos) {
  f();
}