A good JavaScript example [reproduced]

/ / -------------------------------------------------------------------------------------------- ---- Space Judgment Function IsWhitespace (S) {var white = "/ t / n / r"; var i; for (i = 0; i = 0) {return true;}}

Return false;}

/ / -------------------------------------------------------------------------------------------- ---- Leap year judgment function isleApyear (thisyear) {return ((Thisyear% 4 == 0) && (thisyear% 100! = 0)) || (thisyear% 400 == 0))

}

/ / -------------------------------------------------------------------------------------------- ---- Function ischarsinbagex (S, Bag) {VAR I, C; // search through string's character is in bag, append to returbtring.for (i = 0; I -1) Return C;} Return ";

/ / -------------------------------------------------------------------------------------------- ---- Whether to select a radio button Function Radioselected (Radiobth) {for (i = 0; I

/ / -------------------------------------------------------------------------------------------- ---- Year judgment function isyear (s) {var today = new date () thisyear = Today.GetyEAR () var badchar = "> <, [] {}? / = | // '/" :; ~ ! @ # $% ^ & `"; var len = s.Length; if (ISEMPTY (S)) {Alert ("must enter the year") Return False;}} (ischarsinbag (s, badchar)) {Alert (" Years Input Illegal ") Return False;} = ((" "l!"); Return false;} if (! Ischarsinbag (s, "0123456789")) {Alert (" Please check if your year is a number! "); Return false;} if (S <1800) {Alert (" Year of 1800 "); Return False;} //iff ((THISYEAR-S) <0 ) {// alert ("year must not be greater than" thisyear); // return false; //} return true;} // -------------------- ------------------------------ Email Judgment Function ISEMAIL (ISEMPTY (S)) {Alert (" The input E-mail address cannot be empty, please enter! "); Return False;} // iswhitespace (s)) {alert (" Input E-mail address can not contain space characters, please re- Enter! "); Return False;} var i = 1; var len = s.gength;

IF (len> 40) {alert ("E-mail address length can not exceed 40!"); return false;}

POS1 = S.Indexof ("@"); POS2 = S.Indexof ("."); POS3 = S.lastIndexof ("@"); POS4 = S.lastIndexof ("."); if ((((POS1 <= 0) || (POS1 == LEN) || (POS2 <= 0) || (POS2 == LEN)) {Alert ("Please enter a valid E-mail address!"); Return false;} else {ix ((POS1 == POS2 - 1) || (POS1 == POS2 1) || (POS1! = POS3) // Find TWO @ || (POS4

if (! isCharsInBag (s, ".-_ ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 @")) {alert ( "email address only contain characters ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-_@/n" "please re-enter"); return false;} return true; } // ----------------------------------------------------------------------------------------------------------------------------------------------------- --- Digital judgment Function isnum (s) {if (ISEMPTY (S)) {Alert ("must enter a number") Return False;} if (! Ischarsinbag (s, "0123456789")) {Alert ("Please check Whether you entered is a number! "); Return false;} // if (S <1) {// alert (" The input number is greater than 0! "); // Return false; ///} // IF ( S> 2000) {// alert ("The input number is less than 2000!"); // Return False; //} return true;

/ / -------------------------------------------------------------------------------------------- - ID card judgment function iscardNum (s) {if (ISEMPTY (S)) {Alert ("must enter a number") Return False;} if (! Ischarsinbag (s, "0123456789")) {Alert ("Please check Are you entered? Quot;); return false;} if (s.Length == 15 || s.length == 18) {return true;} else {Alert ("The number of input numbers is 15 or 18-bit! "); Return false;}}

/ / -------------------------------------------------------------------------------------------- - Zip code judgment Function iszipcode (s) {if (! ISempty (s)) {if (! Ischarsinbag (s, "0123456789")) {Alert ("Please check if you entered is a number!"); Return False;}} (sLength == 6) {Return true;} else {alert ("The input postal code length is 6!"); return false;}} else {return true;}}}}}}

/ / -------------------------------------------------------------------------------------------- - Date judgment Function Chkdate (DateStr) {if (ISempty ("must enter the date") Return False;} var lthdatestrlthdateStr = DATESTR.LENGTH; var TMPY = "; var TMPM =" "; var TMPD = ""; // var status; status = 0;

For (i = 0; i 2) {alert ("Please use '-' as separator! "); return false;} if (status == 0) && (dateStr.Charat (i)! = '-')) {tmpy = tmpy dateStr.Charat (i)} if ((status == 1) && (DateStr.Charat (i)! = '-')) {TMPM = TMPM DATESTR.CHARAT (i)} f ((status == 2) && (dateStr.Charat (i)! = '-'))) {TMPD = TMPD dateStr.Charat (i)}} Year = new string (tmpy); Month = new string (tmpm); day = new string (tmpd) ​​// Tempdate = new string (YEAR MONTH DAY); // Alert (Tempdate); IF ((TMPy.Length! = 4) || (TMPM.LENGTH> 2) || (TMPD.LENGTH> 2)) {Alert ("Please use '-' as separator!" ); // Alert ("Error Date Format!"); Return False;} If (! ((1 <= MONTH) && (12> = MONTH) && (1 <= day) )) {Alert ("Error Month or Number!"); Return False;} IF (! ("(Year% 4) == 0) && (Month == 2) && (day == 29)) {Alert "This year is not a leap year!"); Return False;} IF ((MONTH <= 7) && ((Month% 2) == 0) && (day> = 31)) {Alert ("This month is only 30 days ! "); Return False;} IF ((Month> = 8) && ((MONTH% 2) == 1) && (day> = 31)) {Alert (" This month is only 30 days! "); Return False } IF ((MONTH == 2) && (day == 30)) {alert ("Didn't this day in February!"); Return False;

Return True;}