Introduction to functions commonly used in js regular expressions
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1. The usage of replace function of js regular expression:
Function function: the replace function returns a copy of the string after text replacement according to the regular expression.
Function format: stringObj.replace (rgExp, replaceText)
Parameters: string stringObj,rgExp regular expression, what is replaced by replaceText
The contents of this module include string creation, regular expression implicit object creation, regular expression creation, and replace method matching.
Sample code:
/ / the contents of the string to be replaced var objStr=new String ("Designed By Androidyue"); / / implicitly create a regular expression object var reG=/e/w?/g;// global match (g is the global match parameter), match e or e? The content var re=/e/w?/;// does not specify a parameter, and the value matches once with (document) {write ("string before matching" + objStr+ "
"); write (" string with global matching "+ objStr.replace (reG," * ") +"
"); write (" match, no parameter value specified for a match "+ objStr.replace (re," × ");}
II. The usage of test function of js regular expression
Function description: the return value of this method is a Boolean value, through which you can match whether the string exists in the regular expression matching result. If there is a match, return ture. If there is no match, return false. This method is often used to judge the validity of user input data, such as verifying the legitimacy of Email.
Basic syntax:
ObjReg.test (objStr)
ObjReg required RegExp object name
The string to be matched by the objStr
Sample code:
/ * Designed By Androidyue*/ / * function: check the validity of Email address * / function checkEmail () {/ / get the information var objStr=document.getElementById ("email") entered by the user in the text box. Value; / / set the regular expression var objReg=//w+ [@] {1} / w + [.] / objStr that matches Email; / / [xss_clean] (objStr) / / if you judge whether there is a match in the string, if there is a correct message, the error if (objReg.test (objStr)) {alert ("the Email address is legal!");} else {alert ("the Email address is illegal!");}} enter the Email address:
