javascript String object_javascript skills

String methods in Javascrīpt:
1. Change string case
string.toUpperCase();
string.toLowerCase();
2. String search
indexOf() method Used to determine whether a short string is in another long string. If it exists, the position index is returned; if it does not exist, the value -1 is returned.
Usage: long string.indexOf("short string")
3. Extract character copies and substrings
The charAt() method can extract a single character from the specified position in the string.
The substring() method can be used to extract a continuous string, and the starting and ending positions need to be provided (Note: The characters at the ending position are not included in the extracted substring.)