A detailed description of common JavaScript string methods

String

A string is one or more characters arranged together, placed in single or double quotation marks.

' ABC '
"ABC"

Length Property

The string in JS is similar to an array, which is made up of a single character, so the length of the string can be obtained with the length property.

var str = "Hello"
Str.length; 5

Some common methods of string

1. CharAt ()

1 str.charat (n)

= = Returns the nth character of a string, or an empty string if it is not between 0~str.length-1.

1 var str = "JavaScript"; 2 // ' V ' 3 // '

2. IndexOf ()

1 indexOf (Substr[,start])

= = Returns the position of the first occurrence of the substr in the string str, starting from the start position, or 1 if it does not exist.

Start can be any integer and the default value is 0. If start < 0 finds the entire string (as if it were passed in 0). If start >= str.length, the method returns-1 unless the string being looked up is an empty string, which returns STR.LENGTH.

1 var str = "JavaScript"; 2 // 1 3 // -1 4 // Ten 5 // 8

3. LastIndexOf ()

1 lastIndexOf (Substr[,start])

= > Returns the position of the last occurrence of the substr in the string str, starting from the start position, and returns 1 if it does not exist.

1 ' lastindex '. LastIndexOf (' a '); // 1

4. SUBSTRING ()

1 str.substring (start[, end])

= > Returns the character from start to end (not included), and start and end are non-negative integers. If the end parameter (end) is omitted, it is truncated from the start position to the last.

1 var str = ' ABCDEFG '; 2 // "BCD" 3 // "BCDEFG" 4 // "ABCDEFG" is treated as 0 when a negative value is passed in

5. Slice ()

1 str.slice (Start[,end])

= > Returns the character from start to end (not included), which can be passed negative

1 var str = ' This is awesome '; 2 Str.slice (4,-1); // "is Awesom"

6. substr ()

1 str.slice (Start[,end])

= > Returns a substring from the specified position in STR to a specified length, start can be negative

1 var str = "Just give me a Reason"; 2 // "Give me a" 3 // "as"

7. Replace ()

1 str.replace (regexp|substr, newsubstr| function)

= > Replace substring of str

1 var str = "Do It Love Me"; 2 str.replace (' Love ', ' hate '); // "Do you Hate Me"

8. Search ()

1 str.search (regexp)

= > Finds if str matches a regular expression. If the match succeeds, the index of the first occurrence of the regular expression in the string is returned; otherwise, 1 is returned. If the parameter passes in an non-regular expression object, it is implicitly converted to a regular expression object using new RegExp (obj)

1 var str = ' I love javascript! ' ; 2 // -1 3 // 7 4 // 7 5 // 7

9. Match ()

1 str.match (regexp)

= > Returns an array containing the matching results, or null if there are no matches. If the parameter passes in an non-regular expression object, it is implicitly converted to a regular expression object using new RegExp (obj)

1 var str = ' Javascript java '; 2 // ["Java"] 3 // ["Java", "Java"] 4 // NULL

Split ()

1 str.split ([separator][, limit])

= > Returns an array where the delimiter separator can be a string or regular expression

1 var str = "Hello?" world! " ; 2 // ["Hello? world! "] 3 // ["H", "E", "L", "L", "O", "?", "W", "O", "R", "L", "D", "!"] 4 // ["Hello", "world!"] 5 // ["H", "E", "L", "L", "O"]

Trim ()

1 str.trim ()

= > Remove white space characters at the beginning and end of STR, returning a copy of STR without affecting the value of the string itself

1 var str = ' abc '; 2 // ' abc ' 3 // ' abc '

toLowerCase ()

1 str.tolowercase ()

= > Converts str to lowercase and returns a copy of STR without affecting the value of the string itself

1 var str = ' JavaScript '; 2 // ' JavaScript ' 3 // ' JavaScript '

toUpperCase ()

1 str.touppercase ()

= > Converts str to uppercase and returns a copy of STR without affecting the value of the string itself

1 var str = ' JavaScript '; 2 // ' JAVASCRIPT ' 3 // ' JavaScript '

A detailed description of common JavaScript string methods