JavaScript method to determine whether a string contains a specified substring_javascript skills

The example in this article describes how JavaScript determines whether a string contains a specified substring. Share it with everyone for your reference. The specific analysis is as follows:

The following JS code defines a contains method for the String object to determine whether the string contains substrings, which is very useful.

if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(obj, start) {
     for (var i = (start || 0), j = this.length; i < j; i++) {
       if (this[i] === obj) { return i; }
     }
     return -1;
  }
}
if (!String.prototype.contains) {
  String.prototype.contains = function (arg) {
    return !!~this.indexOf(arg);
  };
}

The following is a detailed usage example, which can be executed in the browser

Copy code The code is as follows:

Enter two strings and check if Strign 1 contains String 2.
< br>
String 1:  

String 2:


Click to check if String 1 contains String 2
<script><br> if (!Array.prototype.indexOf) {<br> Array.prototype.indexOf = function(obj, start) {<br> for (var i = (start || 0), j = this.length; i < j; i ) {<br /> If (this[i] === obj) { return i; }<br />          }<br />           return -1;<br /> }<br /> }<br /> if (!String.prototype.contains) {<br /> String.prototype.contains = function (arg) {<br />           return !!~this.indexOf(arg);<br /> };<br /> }<br /> function checkstring() {<br /> var foo = document.getElementById("foo").value;<br /> var bar = document.getElementById("bar").value;<br /> alert(foo.contains(bar));<br /> }<br /> </script>

I hope this article will be helpful to everyone’s JavaScript programming design.