Different ways of assigning the same value to different variable declarations

same-value-different-variable.md

Different ways of assigning the same value to different variable declarations

Assignment waterfall

const x = y = z = Symbol('hi');

console.log(x === y && y === z);

Object destructuring assignment with renamed variable names

const { value: x, value: y, value: z } = { value: Symbol('hi') };

console.log(x === y && y === z);

Array destructuring assignment with handrolled array

const [x, y, z] = (function() {
  const value = Symbol('hi');
  return [value, value, value];
})();

console.log(x === y && y === z);

Array destructuring assignment with generator function

const [x, y, z] = (function*() {
  const value = Symbol('hi');
  while(true) {
    return value;
  }
})();

console.log(x === y && y === z);

Object destructuring assignment with handrolled object

const { x, y, z } = (function() {
  const value = Symbol('hi');
  return {
    x: value,
    y: value,
    z: value,
  };
})();

console.log(x === y && y === z);

Object destructuring assignment with proxied object

const { x, y, z } = new Proxy({ value: Symbol('hi') }, {
  get(target) {
    return target.value;
  }
});

console.log(x === y && y === z);

Array destructuring assignment with proxy acting as generator

const [x, y, z] = new Proxy({ value: Symbol('hi') }, {
  get(target, prop, receiver) {
    if (prop === Symbol.iterator) {
      return () => receiver;
    }
    if (prop === 'next') {
      return () => ({
        done: false,
        value: target.value
      })
    }
  }
});

console.log(x === y && y === z);