Detailed discussion of String object in Javascript_javascript skills

The Sting string object is one of the built-in objects provided by Javascript.

Pay special attention here, the first character in the string is the 0th character, and the second character is the 1st character.

1. Method to create a string object

[var] String object instance name = new String(string)

or var String object instance name = string Value

Example:

var str = "Hello World";

var str1 = new String("This is a string");

2 .String property

length: Returns the length of the string

var intlength = str.length //intlength = 11

3.String method

charAt(*): Returns the single character at the *th position of the string

var x = "abcdefg"; var y = x.charAt(3); //y="d"

charCodeAt(*): Returns the ASCII code of a single character in the *th position of the string

No further description

Copy code The code is as follows:

fromCharCode(): Accepts a specified Unicode value and returns a string.

document.write(String.fromCharCode(72,69,76,76,79)); //The output result is HELLO

indexOf(): Find another character from the string String object, the position is returned if the search is successful, otherwise -1 is returned

document.write("children".indexOf("l",0)); //The output result is 3

document. write("children".indexOf("l",1)); //The output result is 3

document.write("children".indexOf("l",4)); //The output result Is -1

lastIndexOf(): Similar to the indexOf() method, except that the search direction is opposite, searching from back to front

document.write("children".lastIndexOf("l ",4)); //The output result is 3

split (separator character): Returns an array. The array is separated from the string. The separator character determines where to separate. .

'l&o&v&e'.split('&'); //Returns the array l,o,v,e

substring(): Equivalent to the cutting function of string

substring([,])

document.write("children".substring(1,3)); //The output result is hil

substr(): also equivalent to cropping, please note the difference with substring()

substr([,])

Copy code The code is as follows:

document.write("children".substr(1,3)); //The output result is hil. It should be noted here that compared with substing, although the results are the same, the algorithms and ideas are different.

toLowerCase() and toUpperCase(): have similar functions, except that they return a string with the same original string. The only difference is that all letters in the former are lowercase and in the latter are uppercase.

document.write("LOVE".toLowerCase()); //The output result is love

document.write("love".toUpperCase()); //The output result is LOVE