js closure memory leak and fix demo

js-closure-memory-leak-and-fix.js

function test() {
  //very long string
  let s = new Array(1000 * 500).join(new Array(1000).join('x'));

  window.check = function() {}//closure

  let out = setTimeout(_ => {
    if (window.check) {
      
      //random index
      let i = Math.round(Math.random() * 5E5);
      console.log(s[i])
      //s = null //fix memory leak
    }

    clearTimeout(out)
  }, 5 * 1000)

}

test()