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Simply learn the for statement loop structure in JavaScript_Basic knowledge

WBOY
WBOYOriginal
2016-05-16 15:32:531397browse

You can just look at the example, it’s used too much, it’s very simple

(function() {
  for(var i=0, len=demoArr.length; i<len; i++) {
    if (i == 2) {
      // return;  // 函数执行被终止
      // break;  // 循环被终止
      continue; // 循环被跳过
    };
    console.log('demo1Arr['+ i +']:' + demo1Arr[i]);
  }
})();

There are a few things to note about the for loop

  • i in the for loop still exists in the scope after the loop ends. In order to avoid affecting other variables in the scope, it is isolated using self-execution of the function ()();
  • Avoid using for(var i=0; i
  • var i = 0, len = demo1Arr.length;
  • for(; i

There are several ways to break out of the loop

  • return function execution is terminated
  • break loop is terminated
  • continue loop is skipped

Full example: 

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>遍历详解: for</title>
 <script src="../script/jquery-2.0.3.js"></script>
</head>
<body>
 
</body>
<script>
 var demo1Arr = ['Javascript', 'Gulp', 'CSS3', 'Grunt', 'jQuery', 'angular'];
 (function() {
 for(var i=0, len=demo1Arr.length; i<len; i++) {
  if (i == 2) {
  // return;  // 函数执行被终止
  // break;  // 循环被终止
  continue; // 循环被跳过
  };
  console.log('demo1Arr['+ i +']:' + demo1Arr[i]);
 }
 })();
</script>
</html>

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