Detailed explanation of the replace method in javascript regular expressions

Detailed explanation of the replace method in javascript regular expressions_javascript skills

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Release： 2016-05-16 16:03:14

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In the previous article, I have introduced the four basic methods of regularization, and I also mentioned the replace method at that time

Let’s review the use of the replace method:
First define a regular object: var re=/write the matching conditions in the middle/;
replace(): Regularly match strings. If the match is successful, replace the successfully matched string with a new string
Syntax: string.replace(re, new string);

For example: It is often encountered on the Internet that uncivilized words will be replaced by *. Let’s try it:

<!DOCTYPE>
<html>
<head>
  <meta charset='utf-8'> 
  <title></title>
</head>
<script type="text/javascript">
window.onload=function(){
  var oTxtarea=document.getElementsByTagName('textarea');
  var oInpt=document.getElementById('bt');
  var re=/你妹|fuck|你大爷|萌萌/g;
  oTxtarea[0].value='我要看你妹，不行，你大爷，我要萌萌你妹，不行，你想想的太多了';
  oInpt.onclick=function(){  
    oTxtarea[1].value=oTxtarea[0].value.replace(re,'*');
  };  
};
</script>
<body>
  <textarea rows='7' cols='20'>
  </textarea><br />
  <input id='bt' type='button' value='转化不文明的语言'><br />
  <textarea rows='7' cols='20'>
  </textarea><br />
</body>
</html>

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Of course, we are not satisfied with the above conversion effect. What I want to achieve is to display several * signs after converting a few words

At this time we need to analyze. In fact, parameter 2 in replace(parameter 1, parameter 2) can be a callback function. Let’s transform the program, replace the second parameter with a callback function, and give This callback function passes a parameter

<!DOCTYPE>
<html>
<head>
  <meta charset='utf-8'> 
  <title></title>
</head>
<script type="text/javascript">
window.onload=function(){
  var oTxtarea=document.getElementsByTagName('textarea');
  var oInpt=document.getElementById('bt');
  var re=/你妹|fuck|你大爷|萌萌/g;
  oTxtarea[0].value='我要看你妹，不行，你大爷，我要萌萌你妹，不行，你想想的太多了';
  oInpt.onclick=function(){  
    oTxtarea[1].value=oTxtarea[0].value.replace(re,function(obj){
        alert(obj);
        /*alert(obj.length);*/
    });
  };  
};
</script>
<body>
  <textarea rows='7' cols='20'>
  </textarea><br />
  <input id='bt' type='button' value='转化不文明的语言'><br />
  <textarea rows='7' cols='20'>
  </textarea><br />
</body>
</html>

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It can be seen that the above result is very strange. The second parameter is the callback function, but when the parameters in the callback function are displayed, they are all successfully matched strings

Then we can process each result in this parameter, and a few words will generate several * signs

<!DOCTYPE>
<html>
<head>
  <meta charset='utf-8'> 
  <title></title>
</head>
<script type="text/javascript">
window.onload=function(){
  var oTxtarea=document.getElementsByTagName('textarea');
  var oInpt=document.getElementById('bt');
  var re=/你妹|fuck|你大爷|萌萌/g;
  oTxtarea[0].value='我要看你妹，不行，你大爷，我要萌萌你妹，不行，你想想的太多了';
  oInpt.onclick=function(){  
    oTxtarea[1].value=oTxtarea[0].value.replace(re,function(obj){
        var a='';
        for (var i = 0; i < obj.length; i++) {
          a+='*';
        }
        return a;
    });
  };  
};
</script>
<body>
  <textarea rows='7' cols='20'>
  </textarea><br />
  <input id='bt' type='button' value='转化不文明的语言'><br />
  <textarea rows='7' cols='20'>
  </textarea><br />
</body>
</html>

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Through the above example, have you deepened your understanding of the replace method? . . . .

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