javascript - 如果使用函数调用执行严格模式函数，则其 'this' 值将是未定义的

Question

我在使用 jshint 时收到以下警告。为什么？

If a strict mode function is executed using function invocation, its 'this' value will be undefined.

function demo() {
    'use strict';

    document.querySelector('#demo').addEventListener('click', test);

    function test() {
        console.log(this);
    }
}

Answer 1

这对我有用

function demo() {
  'use strict';

  var that = this; //new line

  document.querySelector('#demo').addEventListener('click', test);

  function test() {
    console.log(that); //print that instead of this
  }
}