<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<script>
// NULL表示没有值，那么很明显它不能作为任何东西的实例
console.log(typeof null) // object
console.log(null instanceof Object) // false // NaN 即not a numbaer
console.log(typeof NaN) // number
console.log(NaN === NaN) // false // 空数组实际上等于true，但是在和布尔值比较时，却被看作false
var someVar = []
console.log(someVar == false)
if (someVar) {
console.log('hello')
} // 正则表达式
console.log('10 13 21 48 52'.replace(/\d+/g, '*'))
console.log('10 13 21 48 52'.replace(/\d+/g, function(match) {
return parseInt(match, 10) < 30 ? '*' : match
}))
console.log(/\w{3,}/.test('Hello'))
function findWord(word, string) {
var instancesOfWord = string.match(new RegExp('\\b' + word + '\\b', 'ig'))
console.log(instancesOfWord)
}
findWord('car', 'Carl went to buy a car but had forgotten his credit card.') var animal = 'dog'
function getAnimal(adjective) {
console.log(adjective + ' ' + this.animal)
}
var myObj = {
animal: 'camel'
}
getAnimal.call(myObj, 'lovely') var someVar = 'hello'
setTimeout((function(someVar) {
return function() {
console.log(someVar)
}
})(someVar), 1000)
someVar = 'goodbye' console.log(0.1 + 0.2)
</script>
</body>
</html>