88 lines
1.3 KiB
HTML
88 lines
1.3 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="UTF-8">
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<title>Document</title>
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</head>
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<body>
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<script>
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//Oject
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//对象结构 -->字典
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// let obj = {n:"hello 对象"};
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//增加
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// obj.xxx= "你是xxx";
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//改
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// obj.n="滚";
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//删
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// delete obj.xxx;
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//查
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// console.log(obj.n);
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// for( let key in obj){
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// }
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//数组结构---列表
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// let arr = [1,2,3,4,5,6,7];
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// console.log(arr);
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//长度
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// console.log(arr.length);
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//单纯循环
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// arr.forEach((el,i) => {
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// console.log("数组下表项"+el,'下标'+i);
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// })
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//查找(只针对简单数据类型)
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// console.log(arr.includes(7));
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// console.log(arr.includes(17));
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//映射
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// let ar0=arr.map((el,i) => {
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// console.log("数组下标项"+el,'下标'+i);
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// return {项:el,下标:i};
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// })
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//增
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//头部
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arr.unshift('0');
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//尾部
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arr.push("8");
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//删
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//头部删
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arr.shift();
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//尾部删
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arr.pop();
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//指定删
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arr.splice(1,2); //参数一:下标位置 , 参数二:删除几个
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//改
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arr[1]="2";
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//查
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console.log(arr[3]);
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console.log(arr);
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</script>
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</body>
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</html> |