JavaScript：函数、函数表达式、对象、方法和 this

function hello() {  console.log('hello there stranger, how are you?');}hello();

function greet(person) {  console.log(`hi there ${person}.`);}greet('megan');

function greetfullname(fname, lname) {  console.log(`hi there ${fname} ${lname}.`);}greetfullname('megan', 'paffrath');

const square = function(x) {   return x * x;};square(2); // 4

function calltwice(func) {  func();  func();}let laugh = function () {  console.log('haha');};calltwice(laugh);// haha// hahafunction rolldie() {  const roll = math.floor(math.random() * 6) + 1;  console.log(roll);}calltwice(rolldie);// random number// random number

function makemysteryfunc() {  const rand = math.random();  if (rand > 0.5) {    return function () {      console.log('you win');    };  } else {    return function () {      alert('you have been infected by a computer virus');      while (true) {        alert('stop trying to close this window.');      }    };  }}let returnedfunc = makemysteryfunc();returnedfunc();

function makebetweenfunc(min, max) {  return function (num) {    return num &gt;= min &amp;&amp; num <h2>      方法</h2><p>我们可以添加函数作为对象的属性（这些称为方法）。</p><p>例如：<br></p><pre class="brush:php;toolbar:false">const mymath = {  pi: 3.14,  square: function (num) {    return num * num;  },  // note the 2 diff ways of defining methods  cube(num) {    return num ** 3;  },};

const person = {  first: 'abby',  last: 'smith',  fullname() {    return `${this.first} ${this.last}`;  },};person.fullname(); // "abby smith"person.lastname = 'elm';person.fullname(); // "abby elm"

// defined on its own (outside of an object)function howdy() {  console.log('HOWDY');}this.howdy(); // HOWDY