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2.1 Array类型5.html

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>


</head>
<body>
	<input type="text" name="">
	<span></span>
	<script type="text/javascript">
		score = [
		{name:"xu",sc:88},
		{name:"su",sc:5},
		{name:"cu",sc:66}

		]
		/*
		let tf = score.every(item=>{
			if(item.js>=60)
				{console.log(item.sc+"及格")
			return true
		}else{
			console.log("不及格")
			return true
		}

	})*/
		//every()用法
		let tf = score.every(item=>{
			// console.log(item.sc)
			return item.sc>=60
		})
		console.log(tf?"及格":"有不及格")
		//some()用法
		let res = score.some(item=>{
			return item.sc>=60
		})
		console.log(res?"及格":"有不及格")


		// 示例 规范化输出提示
		guize = ["xu","1959"]
		val = document.querySelector("input")
		span = document.querySelector("span")
		val.addEventListener("keyup",function(){
			guize.some(item=>{
				span.innerHTML = val.value.includes(item)?"":"不含关键字"+guize.join("和")

			})
		})

		//filter过滤元素 (提取指定元素)
		score = [
		{name:"xu",sc:88},
		{name:"su",sc:5},
		{name:"cu",sc:66}

		]
		console.table(score.filter(item=>{
			return item.name == "su"
		}))

		//filter实现原理(1)
		/*let arr = [1,2,3,5]
		function filter(array,except){
			let newArray =[]
			//获取数组的每个值
			for (const item of array){

				if(except.includes(item)===false){newArray.push(item)

				}
			}
			return newArray
		}
		console.log(filter(arr,[1,2]))*/


		//filter实现原理(2)
		let arr = [1,2,3,5]
		function filter(array,callback){
			let newArray =[]
			//获取数组的每个值
			for (const item of array){

				if(callback(item)===false){newArray.push(item)

				}
			}
			return newArray
		}
		console.log(filter(arr,function(item){
			return item<5
		}))

		//map 映射 对数组进行二次操作
		//可看情况用来修改引用类型或添加新数组
		console.log("-------map1 str不变--------")

		let maparr1 =["xu","su"]
		let newarr1 = maparr1.map(item=>{item = "new"+item
			return item})

		console.log("maparr1  ↓")
		console.table(maparr1)
		console.log("New arrmap1  ↓")
		console.table(newarr1)

		console.log("-------map2 obj变--------")

		let maparr2 =[{name:"xu"},{name:"su"}]
		let newarr2 = maparr2.map(item=>{
			item.click =100
			return item
		})


		console.log("maparr2  ↓")
		console.table(maparr2)
		console.log("New arrmap2  ↓")
		console.table(newarr2)

		console.log("-------map2 obj不变--------")

		let newarr3 = maparr2.map(item=>{

			//Object 对象的合并assign(target,sources)!!注意顺序
			return Object.assign({hai:100},item)
		})

		console.log("maparr2  ↓")
		console.table(maparr2)
		console.log("New arrmap3  ↓")
		console.table(newarr3)
		console.log("-------reduce--------")
		//reduce 使用 pre是每次返回值 默认为数组第一个或默认值
		let redarr = [1,2,3,55,9,2,2,10]
		redarr.reduce(function(pre,item,index,array){
			console.log(`pre:${pre},item:${item}`)
			return 55
		},0)
		// 示例 或取max值
		function maxarr(arr,pre=0){
			return arr.reduce(function(pre,item){
				return pre>=item?pre:item
			},pre)
		}
		console.log(maxarr(redarr))

		//示例 获取和
		function totalarr(arr,pre=0){
			return arr.reduce(function(pre,item){
				return pre+=item
			},pre)
		}
		console.log(totalarr(redarr))
		//示例 统计次数
		function totalarr2(arr,pre=0,ci){
			return arr.reduce(function(pre,item){
				// console.log(pre,item,ci)
				return ci==item?pre+=1:pre+=0
			},pre)
		}
		console.log(totalarr2(redarr,0,2))
	</script>
</body>
</html>