20 commonly used string methods in JavaScript (Collection)

This article will introduce to you 20 commonly used JavaScript string methods worth collecting. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

1. charAt(x)

charAt(x)Returns the character at position x in the string, subscript Start at 0.

    //charAt(x)
    var myString = 'jQuery FTW!!!';
    console.log(myString.charAt(7));
    //output: F

2. charCodeAt(x)

`charCodeAt(x)`返回字符串中`x`位置处字符的`unicode`值。

    //charAt(position)
    var message="jquery4u"
    //alert "113"
    alert(message.charAt(1)

3. concat(v1,v2..)

concat() The method is used to concatenate two or more strings. This method does not change the existing string and returns the new string after splicing.

    //concat(v1, v2,..)
    var message="Sam"
    var final=message.concat(" is a"," hopeless romantic.")
    //alerts "Sam is a hopeless romantic."
    alert(final)

4. fromCharcode(c1,c2)

fromCharcode(c1,c2)Convert a set of Unicode values Convert to character.

    //fromCharCode(c1, c2,...)
    console.log(String.fromCharCode(97,98,99,120,121,122))
    //output: abcxyz
    console.log(String.fromCharCode(72,69,76,76,79))
    //output: HELLO

5. indexOf(substr, [start])

indexOf method searches and (if found) returns the searched string Index of a character or substring. If not found, -1 is returned. Start is an optional parameter that specifies the position in the string to start searching. The default value is 0.

    //indexOf(char/substring)
    var sentence="Hi, my name is Sam!"
    if (sentence.indexOf("Sam")!=-1)
    alert("Sam is in there!")

6. lastIndexOf(substr, [start])

lastIndexOf() method returns the last occurrence of the specified text in the string Index, if not found, returns -1. "Start" is an optional parameter that specifies the position in the string to start searching. The default value is string.length-1.

    //lastIndexOf(substr, [start])
    var myString = 'javascript rox';
    console.log(myString.lastIndexOf('r'));
    //output: 11

7. match(regexp)

Search for matches in a string based on a regular expression. If no match is found, an information array or null is returned.

    //match(regexp) //select integers only
    var intRegex = /[0-9 -()+]+$/;  
     
    var myNumber = '999';
    var myInt = myNumber.match(intRegex);
    console.log(isInt);
    //output: 999
     
    var myString = '999 JS Coders';
    var myInt = myString.match(intRegex);
    console.log(isInt);
    //output: null

8. replace(regexp/substr, replacetext)

replace() method is used to replace some characters in a string with another Some characters, or replace a substring that matches a regular expression.

    //replace(substr, replacetext)
    var myString = '999 JavaScript Coders';
    console.log(myString.replace(/JavaScript/i, "jQuery"));
    //output: 999 jQuery Coders
     
    //replace(regexp, replacetext)
    var myString = '999 JavaScript Coders';
    console.log(myString.replace(new RegExp( "999", "gi" ), "The"));
    //output: The JavaScript Coders

9. search(regexp)

search() method is used to retrieve the specified substring in the string, or retrieve the same The substring matched by the regular expression. If found, the starting position of the substring matching regexp is returned, otherwise -1 is returned.

    //search(regexp)
    var intRegex = /[0-9 -()+]+$/;  
     
    var myNumber = '999';
    var isInt = myNumber.search(intRegex);
    console.log(isInt);
    //output: 0

10. slice(start, [end])

slice() method can extract a certain part of the string and return a new string. Includes all characters in the string starting at start (including start) and ending at end (excluding end).

    //slice(start, end)
    var text="excellent"
    text.slice(0,4) //returns "exce"
    text.slice(2,4) //returns "ce"

11. split(delimiter, [limit])

split() method is used to split a string into a string array , returns a string array. The strings in the returned array do not include delimiter itself. The optional "limit" is an integer that allows you to specify the maximum number of elements in the array to be returned.

12. substr(start, [length])

substr() method can extract from the string start The specified number of characters starting from the subscript. Returns a new string containing length characters starting at start, including the character pointed to by start. If length is not specified, the returned string contains characters from start to the end of the string.

    //substring(from, to)
    var text="excellent"
    text.substring(0,4) //returns "exce"
    text.substring(2,4) //returns "ce"

13. substring(from, [to])

substring() method is used to extract the string between two specified The substring returned includes the characters at start, but does not include the characters at stop. to is optional. If this is omitted, parameter, then the returned substring will go to the end of the string.

    //substring(from, [to])
    var myString = 'javascript rox';
    myString = myString.substring(0,10);
    console.log(myString)
    //output: javascript

14. toLowerCase()

toLowerCase() method is used to convert strings to lowercase.

    //toLowerCase()
    var myString = 'JAVASCRIPT ROX';
    myString = myString.toLowerCase();
    console.log(myString)
    //output: javascript rox

15. toUpperCase()

toUpperCase() method is used to convert a string to uppercase.

    //toUpperCase()
    var myString = 'javascript rox';
    myString = myString.toUpperCase();
    console.log(myString)
    //output: JAVASCRIPT ROX

16. includes()

includes() method is used to check whether the string contains the specified string or character.

    //includes()
    var mystring = "Hello, welcome to edureka";
    var n = mystring.includes("edureka");
    //output: True

17. endsWith()

endsWith()The function checks whether the string ends with the specified string or character.

    //endsWith()
    var mystr = "List of javascript functions";
    var n = mystr.endsWith("functions");
    //output: True

18. repeat()

repeat() Constructs and returns a new string containing the concatenated Makes a specified number of copies of a string.

    //repeat()
    var string = "Welcome to Edureka";
    string.repeat(2);
    //output: Welcome to Edureka Welcome to Edureka

19. valueOf()

valueOf() method returns the primitive value of a String object ), this value is equivalent to String.prototype.toString().

    //valueOf()
    var mystr = "Hello World!";
    var res = mystr.valueOf();
    //output: Hello World!

20. trim()

trim() method removes whitespace characters from both ends of a string. Whitespace characters in this context are all whitespace characters (space, tab, no-break space, etc.) and all line terminator characters (such as LF, CR)

    //trim()
    var str = "     Hello Edureka!     ";
    alert(str.trim());

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