Javascript string operator _ javascript skills

Summary of js string operation functions. Concat ()-combines two or more characters to return a new string.
IndexOf ()-returns the index at the first part of a substring in a string. If no match exists,-1 is returned.
CharAt ()-returns the character at the specified position.
LastIndexOf ()-returns the index of the last occurrence of a substring in the string. If no match exists,-1 is returned.
Match ()-check whether a string matches a regular expression.
Substring ()-returns a substring of a string. The input parameters are the start position and end position.
Replace ()-used to find a string that matches a regular expression, and then use a new string to replace the matched string.
Search ()-execute a regular expression to match the search results. If the search is successful, the matching index value in the string is returned. Otherwise,-1 is returned.
Slice ()-extract part of the string and return a new string.
Split ()-divides a string into substrings to form a string array.
Length-returns the length of a string. The so-called length of a string refers to the number of characters it contains.
ToLowerCase ()-converts the entire string into lowercase letters.
ToUpperCase ()-converts the entire string into uppercase letters.