JavaScript でよくある落とし穴を回避する方法に関するヒントとテクニックの概要

let s = "bob"
const replaced = s.replace('b', 'l')
replaced === "lob" // 只会替换掉第一个b
s === "bob" // 并且s的值不会变

"bob".replace(/b/g, 'l') === 'lol'

// 这些可以
'abc' === 'abc' // true
1 === 1 // true
// 然而这些不行
[1,2,3] === [1,2,3] // false
{a: 1} === {a: 1} // false
{} === {} // false

typeof {} === 'object' // true
typeof 'a' === 'string' // true
typeof 1 === number // true
// 但是....
typeof [] === 'object' // true

const Greeters = []
for (var i = 0 ; i < 10 ; i++) {
 Greeters.push(function () { return console.log(i) })
}
Greeters[0]() // 10
Greeters[1]() // 10
Greeters[2]() // 10

Greeters.push(console.log.bind(null, i))

class Foo {
 constructor (name) {
 this.name = name
 }
 greet () {
 console.log('hello, this is ', this.name)
 }
 someThingAsync () {
 return Promise.resolve()
 }
 asyncGreet () {
 this.someThingAsync()
 .then(this.greet)
 }
}
new Foo('dog').asyncGreet()

asyncGreet () {
 this.someThingAsync()
 .then(this.greet.bind(this))
}

class Foo {
 constructor (name) {
 this.name = name
 this.greet = this.greet.bind(this)
 }
}

asyncGreet () {
 this.someThingAsync()
 .then(() => {
 this.greet()
 })
}

Math.min() < Math.max() // false