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JavaScript code analysis to replace the last character in a string

黄舟Original: 2017-03-22 14:52:341942browse

This article mainly introduces the method of JavaScript to realize the replacement of the last character in string, involving the conversion and operation of javascript strings. Friends who need it can refer to it. Next

The example in this article describes how to replace the last character in a string using JavaScript. Share it with everyone for your reference, the details are as follows:

1. Problem background

In an input box, the string length is limited to 12 digits, use the keyboard to enter a Number, the last digit in the string will be replaced, for example: 111111111111, and then enter a 3, it will display 111111111113

2. Specific implementation

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>JavaScript替换字符串中最后一个字符</title>
<script type="text/javascript">
  function replaceStr()
  {
    var e = event || window.event || arguments.callee.caller.arguments[0];
    var input_str = document.getElementById("input_str").value;
    var newStr = input_str.substring(0,11);
    if(e && e.keyCode>=48 && e.keyCode <= 57)
    {
      newStr += (e.keyCode-48);
    }
    document.getElementById("input_str").value = newStr;
  }
</script>
</head>
<body>
  <input type="text" id="input_str" maxlength="12" onkeyup="replaceStr();"/>
</body>
</html>

3. Implementation result

(1)Initialization

(2)After inputting “3”

4. Implementation method in extended appendix

jQuery:

$("#input_str").keydown(function(event){
  var nums = $("#input_str").val();
  var e = event || window.event || arguments.callee.caller.arguments[0];
  var newStr = nums.substring(0,11);
  if(e && e.keyCode>=48 && e.keyCode <= 57)
  {
    newStr += (e.keyCode-48);
  }
  $("#input_str").val(newStr);
});

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