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Object.keys方法之详解

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  <title>Object.keys方法之详解</title>
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  <h2>Object.keys方法之详解</h2>
  <h3> 一、语法</h3>
  <div>
    <pre>
      Object.keys(obj)

      参数:要返回其枚举自身属性的对象
    
      返回值:一个表示给定对象的所有可枚举属性的字符串数组
     </pre>
  </div>
  <h3>二、处理对象,返回可枚举的属性数组</h3>

  <div>
    <pre>
      let person = { name: ‘tom‘, age: 25, address: ‘南非‘,getName:function(){}}

      Object.keys(person) // ["name", "age", "address","getName"]
     </pre>
    <script>
      let person = { name: ‘tom‘, age: 25, address: ‘南非‘, getName: function () { } }

      console.log(Object.keys(person))
    </script>
  </div>
  <h3>三、处理数组。返回索引值数组</h3>
  <div>
    <pre>
      let arr = [1,2,3,4,5,6]

      Object.keys(arr) // ["0", "1", "2", "3", "4", "5"]
     </pre>
    <script>
      let arr = [1, 2, 3, 4, 5, 6]

      console.log(Object.keys(arr))  // ["0", "1", "2", "3", "4", "5"]
    </script>
  </div>
  <h3>四、处理字符串,返回索引值数组 </h3>
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    <pre>
    let str = "object.obj字符串"

    Object.keys(str) // ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12"]
  </pre>
    <script>
      let str = ‘object.obj字符串‘;
      console.log(Object.keys(str)) //["0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12"]
    </script>
  </div>
  <h3>使用案例</h3>
  <div>
    <pre>
    //get请求
    let url = ‘http://localhost:8081‘
    let data = { name: ‘tom‘, age: 25, address: ‘南非‘ };
    let dataStr = ‘‘;//拼接字符串
    Object.keys(data).forEach(key => {
      dataStr += key + ‘=‘ + data[key] + ‘&‘
    })
    console.log(dataStr)
    if (dataStr !== ‘‘) {//拼接字符串
      dataStr = dataStr.substring(0, dataStr.lastIndexOf(‘&‘))
      url = url + ‘?‘ + dataStr;
      console.log(url)
    }      
    </pre>
    <script>
      //get请求
      let url = ‘http://localhost:8081‘
      let data = { name: ‘tom‘, age: 25, address: ‘南非‘ };
      let dataStr = ‘‘;//拼接字符串
      Object.keys(data).forEach(key => {
        dataStr += key + ‘=‘ + data[key] + ‘&‘
      })
      console.log(dataStr)
      if (dataStr !== ‘‘) {//拼接字符串
        dataStr = dataStr.substring(0, dataStr.lastIndexOf(‘&‘))
        url = url + ‘?‘ + dataStr;
        console.log(url)
      }
    </script>
  </div>
  <h3>五、常用技巧 </h3>

  <div>
    <pre>
    let person = {name:"张三",age:25,address:"深圳",getName:function(){}}

    Object.keys(person).map((key)=>{
  
      person[key] // 获取到属性对应的值,做一些处理
  
    })
   </pre>
  </div>

  <h3> 六、Object.values()和Object.keys()是相反的操作,把一个对象的值转换为数组</h3>
  <div>
    <pre>
    let strList = { name: ‘tom‘, age: 25, address: ‘南非‘ };
    console.log(Object.values(strList))  //["tom", 25, "南非"]
    </pre>
    <script>
      let strList = { name: ‘tom‘, age: 25, address: ‘南非‘ };
      console.log(Object.values(strList))  //["tom", 25, "南非"]
    </script>
  </div>
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Object.keys方法之详解

原文:https://www.cnblogs.com/xpf123/p/11678595.html

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