Usage of substr, substring, indexOf, and lastIndexOf in js
1. substr
Substr (start, length) indicates that the length string is truncated from the start position.
Var src = "images/off_1.png ";
Alert (src. substr (7,3 ));
Pop-up value: off
2. substring
Substring (start, end) indicates the string between start and end, including the start position but not the end position.
Var src = "images/off_1.png ";
Alert (src. substring (7,10 ));
Pop-up value: off
3. indexOF
The indexOf () method returns the position (from left to right) where a specified string value first appears in the string ). If no match exists,-1 is returned. Otherwise, the value of the string that appears for the first time is returned.
Var src = "images/off_1.png ";
Alert (src. indexOf ('T '));
Alert (src. indexOf ('I '));
Alert (src. indexOf ('G '));
The pop-up values are:-1, 0, and 3.
4. lastIndexOf
The lastIndexOf () method returns the index value (opposite to indexOf) of the first character of a character or string that appears from the right to the left)
Var src = "images/off_1.png ";
Alert (src. lastIndexOf ('/'));
Alert (src. lastIndexOf ('G '));
Pop-up values: 6, 15