JavaScript indexOf method entry example (calculates the first occurrence of a specified character in a string)
- 2020-03-30 04:09:10
- OfStack
JavaScript method indexOf
The indexOf method calculates the first occurrence of a specified string in a string and returns the value. The syntax is as follows:
str_object.indexOf( search, start )
Parameter description:
| parameter | instructions |
|---|---|
| str_object | String (object) to manipulate |
| search | A necessity. The string to retrieve |
| start | Optional. Specifies where to start the retrieval, and if the parameter is omitted, the retrieval begins with the first character of the string |
Tip: strings are counted from 0.
Example of the indexOf method
<script language="JavaScript">
var str = "www.jb51.net";
document.write( str.indexOf( "." ) );
</script>
Run the example and output:
3
IndexOf is case-sensitive and returns -1 if the string value to be retrieved does not appear.