Of Stack

JavaScript implements two select drop down box options to move left and right

  • 2021-08-03 08:23:22
  • OfStack

Today nothing with js wrote a small program with two select drop-down box can move elements between each other, just started to learn javascript there are many places to optimize.

Javascript code 


<script type="text/javascript"> 
 
   
  /** The selected element moves to the right **/ 
  function moveRight() 
  { 
     
      // Get the first 1 A select Object  
    var selectElement = document.getElementById("first"); 
    var optionElements = selectElement.getElementsByTagName("option"); 
    var len = optionElements.length; 
   
 
    if(!(selectElement.selectedIndex==-1))  // If no element is selected, then selectedIndex Just for -1 
    { 
       
      // Get the first 2 A select Object  
      var selectElement2 = document.getElementById("secend"); 
   
        //  Move to the right  
        for(var i=0;i<len ;i++) 
        { 
          selectElement2.appendChild(optionElements[selectElement.selectedIndex]); 
        } 
    } else 
    { 
      alert(" You have not selected an element to move! "); 
    } 
  } 
   
  // Move everything to the right  
  function moveAll() 
  { 
    // Get the first 1 A select Object  
    var selectElement = document.getElementById("first"); 
    var optionElements = selectElement.getElementsByTagName("option"); 
    var len = optionElements.length; 
    //alert(len); 
   
    // Will be 1 A selected Array flip in  
    var firstOption = new Array(); 
    for(var k=len-1;k>=0;k--) 
    { 
      firstOption.push(optionElements[k]); 
   
    } 
    var lens = firstOption.length; 
      // Get the first 2 A select Object  
    var selectElement2 = document.getElementById("secend"); 
    for(var j=lens-1;j>=0;j--) 
    { 
      selectElement2.appendChild(firstOption[j]); 
    } 
  } 
   
  // Move the selected element to the left  
  function moveLeft() 
  { 
    // First get the first 2 A select Object  
    var selectElement = document.getElementById("secend"); 
    var optionElement = selectElement.getElementsByTagName("option"); 
    var len = optionElement.length; 
     
    // Get the first place again 1 Elements  
    if(!(selectElement.selectedIndex==-1)) 
    { 
      var firstSelectElement = document.getElementById("first"); 
      for(i=0;i<len;i++) 
      { 
        firstSelectElement.appendChild(optionElement[selectElement.selectedIndex]);// Index of the selected element  
      } 
    }else 
    { 
      alert(" You have not selected an item to move !"); 
    } 
  } 
   
  // Move all to the left  
  function moveAllLeft() 
  { 
    var selectElement = document.getElementById("secend"); 
    var optionElements = document.getElementsByTagName("option"); 
    var len = optionElements.length; 
    var optionEls = new Array(); 
    for(var i=len-1;i>=0;i--) 
    { 
      optionEls.push(optionElements[i]); 
    } 
    var lens = optionEls.length; 
     
    var firstSelectElement = document.getElementById("first"); 
    for(var j=lens-1;j>=0;j--) 
    { 
      firstSelectElement.appendChild(optionEls[j]); 
    } 
  } 
</script>

The above is javascript code, and the following is html plus css code.

Html code 


<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
<title> Untitled document </title> 
<style type="text/css"> 
  .select_move { margin:0px auto; width:206px; height:140px; margin-top:300px;} 
  .select_move_1 { float:left;} 
  .select_move_2 { float:left;} 
  .select_move_3 { float:left;} 
</style> 
</head> 
 
<body> 
  <div class="select_move"> 
   
    <div class="select_move_1"> 
     <select name="first" size="10" id="first" multiple="multiple"> 
      <option value=" BMW "> BMW </option> 
      <option value=" Toyota "> Toyota </option> 
      <option value=" Audi "> Audi </option> 
      <option value=" Cadillac "> Cadillac </option> 
      <option value=" Modern "> Modern </option> 
      <option value=" Mercedes-Benz "> Mercedes-Benz </option> 
      <option value=" Ferrari "> Ferrari </option> 
       
     </select> 
    </div> 
     <div class="select_move_2"> 
        <input type="button" value="------>" onclick="moveRight()"/><br /> 
        <input type="button" value="===>" onclick="moveAll()" /><br /> 
        <input type="button" value="<------" onclick="moveLeft()"/><br /> 
        <input type="button" value="<===" onclick="moveAllLeft()"/> 
     </div> 
    <div class="select_move_3"> 
       <select size="10" id="secend" multiple="multiple"> 
       </select> 
    </div> 
  </div> 
   
</body> 
</html>

Source code download: js to achieve drop-down box elements move each other

Related articles: