// 1.变量（Variables）    var myVariable;    myVariable = 'Bob';    // 数据类型    string     number    boolean    array    object// 2.注释    /*    Everything in between is a comment.    */// 3.运算符    +    -    *    /    =    ===    !    !==  // 4.语句    var iceCream = 'chocolate';    if (iceCream === 'chocolate') {      alert('Yay, I love chocolate ice cream!');        } else {      alert('Awwww, but chocolate is my favorite...');        }// 5.函数    function multiply(num1,num2) {      var result = num1 * num2;      return result;    }    multiply(4,7);// 6.事件    document.querySelector('html').onclick = function() {        alert('Ouch! Stop poking me!');    }