Verify ID card validity using Javascript

Please refer to the instance code for the tutorial of helper House (www.bkjia.com:

Reference content is as follows: <Script language = "javascript"> Function isChinaIDCard (){ StrNo = document. getElementById ("<% = txtCarID. ClientID %>"). value; If (StrNo. length = 15 ){ If (! IsValidDate ("19" + StrNo. substr (6, 2), StrNo. substr (8, 2), StrNo. substr (10, 2) {return false ;} } Else if (StrNo. length = 18 ){ If (! IsValidDate (StrNo. substr (6, 4), StrNo. substr (10, 2), StrNo. substr (12, 2) {return false ;} } Else { ShowLayer ('popupbox', "the ID card number must be 15 or 18 characters! "); Return false; } If (StrNo. length = 18) { Var a, B, c If (! IsNumber (StrNo. substr () {showLayer ('popupbox', "the ID number is incorrect. The first 17 digits cannot contain English letters! "); Return false ;} A = parseInt (StrNo. substr () * 7 + parseInt (StrNo. substr () * 9 + parseInt (StrNo. substr () * 10; A = a + parseInt (StrNo. substr () * 5 + parseInt (StrNo. substr () * 8 + parseInt (StrNo. substr () * 4; A = a + parseInt (StrNo. substr (6, 1) * 2 + parseInt (StrNo. substr (7, 1) * 1 + parseInt (StrNo. substr (8, 1) * 6; A = a + parseInt (StrNo. substr () * 3 + parseInt (StrNo. substr () * 7 + parseInt (StrNo. substr () * 9; A = a + parseInt (StrNo. substr () * 10 + parseInt (StrNo. substr () * 5 + parseInt (StrNo. substr () * 8; A = a + parseInt (StrNo. substr (15,1) * 4 + parseInt (StrNo. substr (16,1) * 2; B = a % 11; If (B = 2) // the last digit is the check bit. { C = StrNo. substr (17,1). toUpperCase (); // convert to uppercase X } Else { C = parseInt (StrNo. substr (17,1 )); } Switch (B) { Case 0: if (c! = 1) {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be: 1"); return false;} break; Case 1: if (c! = 0) {showLayer ('popupbox', "Incorrect ID card number check bit: the last digit should be: 0"); return false;} break; Case 2: if (c! = "X") {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be: X"); return false;} break; Case 3: if (c! = 9) {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be 9"); return false;} break; Case 4: if (c! = 8) {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be 8"); return false;} break; Case 5: if (c! = 7) {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be 7"); return false;} break; Case 6: if (c! = 6) {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be 6"); return false;} break; Case 7: if (c! = 5) {showLayer ('popupbox', "Incorrect ID card number check bit: the last digit should be: 5"); return false;} break; Case 8: if (c! = 4) {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be 4"); return false;} break; Case 9: if (c! = 3) {showLayer ('popupbox', "Incorrect ID card number check bit: the last digit should be: 3"); return false;} break; Case 10: if (c! = 2) {showLayer ('popupbox', "check digit of the ID card is incorrect: the last digit should be: 2"); return false ;} } } Else {// 15-digit ID card number If (! IsNumber (StrNo) {showLayer ('popupbox', "the ID card number is incorrect. The first 15 digits cannot contain English letters! "); Return false ;} } Return true; } Function isValidDate (iY, iM, iD ){ If (iY> 2009 | iY <1900 |! IsNumber (iY )){ ShowLayer ('popupbox', "Enter ID card number, year" + iY + "illegal! "); Return false; } If (iM> 12 | iM <= 0 |! IsNumber (iM )){ ShowLayer ('popupbox', "Enter ID card number, Month" + iM + "illegal! "); Return false; } If (iD> 31 | iD <= 0 |! IsNumber (iD )){ ShowLayer ('popupbox', "Enter iD card number, date" + iD + "illegal! "); Return false; } Return true; } /** * Verify if it is a number. */ Function isNumber (oNum ){ If (! ONum) return false; Var strP =/^ \ d + (\. \ d + )? $ /; If (! StrP. test (oNum) return false; Try { If (parseFloat (oNum )! = ONum) return false; } Catch (ex) { Return false; } Return true; } Function showLayer (id, txt ){ Document.getelementbyid(id).style.height?document.doc umentElement. scrollHeight; Document. getElementById (id). style. display = "block "; Document. getElementById ("txtid"). innerText = txt; Document. body. style. overflow = "hidden "; Document. body. scrollTop = 0; } Function hideLayer (id ){ Document. getElementById (id). style. display = "none "; Document. body. style. overflow = "visible "; } </Script> <! -- Pop-up layer: start --> <Div class = "popupBox" id = "popupBox"> <Iframe class = "popupFrame"> </iframe> <Div class = "popupMask"> </div> <Div class = "popupContent" id = "popupContent"> <H3 id = "txtid"> <Button onclick = "hideLayer ('popupbox')"> </button> </Div> </Div> <! -- Pop-up layer: end -->