数组的操作

Posted 2020-11-19 lovemis

• 创建数组
• <script>
  var i;
  var mycars = new Array();
  mycars[0] = "Saab";
  mycars[1] = "Volvo";
  mycars[2] = "BMW";
  for (i=0;i<mycars.length;i++){
      document.write(mycars[i] + "<br />");
  }
  </script>
• 合并两个数组 - concat()
• <script>
  var hege = ["Cecilie", "Lone"];
  var stale = ["Emil", "Tobias", "Linus"];
  var children = hege.concat(stale);
  document.write(children);
  </script>
• 合并三个数组 - concat()
• <script>
  var parents = ["Jani", "Tove"];
  var brothers = ["Stale", "Kai Jim", "Borge"];
  var children = ["Cecilie", "Lone"];
  var family = parents.concat(brothers, children);
  document.write(family);
  </script>
• 用数组的元素组成字符串 - join()
• <script>
  function myFunction(){
      var fruits = ["Banana", "Orange", "Apple", "Mango"];
      var x=document.getElementById("demo");
      x.innerhtml=fruits.join();
  }
  </script>
• 删除数组的最后一个元素 - pop()
• <script>
  var fruits = ["Banana", "Orange", "Apple", "Mango"];
  function myFunction(){
      fruits.pop();
      var x=document.getElementById("demo");
      x.innerHTML=fruits;
  }
  </script>
• 数组的末尾添加新的元素 - push()
• <script>
  var fruits = ["Banana", "Orange", "Apple", "Mango"];
  function myFunction(){
      fruits.push("Kiwi")
      var x=document.getElementById("demo");
      x.innerHTML=fruits;
  }
  </script>
• 反转一个数组中的元素的顺序 - reverse()
• <script>
  var fruits = ["Banana", "Orange", "Apple", "Mango"];
  function myFunction(){
      fruits.reverse();
      var x=document.getElementById("demo");
      x.innerHTML=fruits;
  }
  </script>
• 删除数组的第一个元素 - shift()
• <script>
  var fruits = ["Banana", "Orange", "Apple", "Mango"];
  function myFunction(){
      var delell = fruits.shift();
      var x=document.getElementById("demo");
      x.innerHTML= ‘删除后数组为：‘ +  fruits;
      document.getElementById("demo2").innerHTML= ‘删除的元素是：‘ +  delell;
  }
  </script>
• 从一个数组中的选择元素 - slice()
• <script>
  function myFunction(){
      var fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
      var citrus = fruits.slice(1,3);
      var x=document.getElementById("demo");
      x.innerHTML=citrus;
  }
  </script>
• 数组排序（按字母顺序升序）- sort()
• <script>
  function myFunction(){
      var fruits = ["Banana", "Orange", "Apple", "Mango"];
      fruits.sort();
      var x=document.getElementById("demo");
      x.innerHTML=fruits;
  }
  </script>
• 数字排序（按数字顺序升序）- sort()
• <script>
  function myFunction(){
      var points = [40,100,1,5,25,10];
      points.sort(function(a,b){return a-b});
      var x=document.getElementById("demo");
      x.innerHTML=points;
  }
  </script>
• 数字排序（按数字顺序降序）- sort()
• <script>
  function myFunction(){
      var points = [40,100,1,5,25,10];
      points.sort(function(a,b){return b-a});
      var x=document.getElementById("demo");
      x.innerHTML=points;
  }
  </script>
• 在数组的第2位置添加一个元素 - splice()
• <script>
  function myFunction(){
      var fruits = ["Banana", "Orange", "Apple", "Mango"];
      fruits.splice(2,0,"Lemon","Kiwi");
      var x=document.getElementById("demo");
      x.innerHTML=fruits;
  }
  </script>
• 转换数组到字符串 -toString()
• <script>
  function myFunction(){
      var fruits = ["Banana", "Orange", "Apple", "Mango"];
      var str = fruits.toString();
      var x=document.getElementById("demo");
      x.innerHTML= str;
  }
  </script>
• 在数组的开头添加新元素 - unshift()
• <script>
  function myFunction(){
      var fruits = ["Banana", "Orange", "Apple", "Mango"];
      fruits.unshift("Lemon","Pineapple");
      var x=document.getElementById("demo");
      x.innerHTML=fruits;
  }
  </script>