JS Regular expression (1)

Define the Regular:

var New REGEXP (' a '); Instantiate objects, parameters are the rules we want to make
var reg =/a/; Shorthand method

Common methods for regular use:

　　1, Test (): Find the content in the string that conforms to the regular, find to return true, reverse return false

　　　　Usage: Regular. Test (string);

Example: Judging whether it is a number

var str = ' 12345678 ';     var // \d represents non-digital    if (Reg.test (str)) {        alert (' Not all numbers ');    } Else {        alert (' all numbers ');    }

2, search (): Searching in the string matches the regular content, the search to return to the location of the occurrence (starting from 0, if the search is not just a letter, the first letter is returned), and vice versa-1

　　　　Usage: string. Search (Regular)

var str = ' Webrty '; var reg =/b/i;     // I means case insensitive Console.log (Str.search (reg));   // returns 2

　　3. Match (): searches the string for regular content, returns the content in a successful match, formats an array, and fails returns null

　　　Usage: string. Match (regular);　　

var str = ' as123msd8xx29shdkdk220nm '; var reg =/\d+/g;   // match at least one number, G means global match Console.log (Str.match (reg));    // ["123", "8" , "$", "$"]

　　4. Replace (): Find the regular string, replace it with the corresponding string, return the replaced content

　　　　usage: string. Replace (regular, new string/callback function); (In a callback function, the first argument is the first character to match)

Example: Sensitive word filtering

var str = ' grapes do not spit on grape skins '; var reg =/Grape | skin/g;  // match grape or skin, global match var str2 = str.replace (Reg, ' * '); Console.log (str2);     // Eat * Don't spit * *

　　To implement several words corresponding to several *, you can use the callback function

varstr = ' grapes do not spit on grape skins ';varreg =/Grape | skin/g;//match grape or skin, global matchvarSTR2 = Str.replace (Reg,function(str) {//The str parameter refers to the grape for the first time, the second refers to the grape, and the third refers to the skin.     varresult = ';  for(vari=0;i<str.length;i++) {result+ = ' * '; }          returnresult;});  Console.log (STR2); //Eat * * NOT spit * * *

JS Regular expression (1)