Common Javascript methods used in HTML to verify form text fields, such as dates, strings, and numbers

// ============== Verification function start <br/> var isie = false; <br/> var isff = false; <br/> var Issa = false; <br/> If (navigator. useragent. indexof ("MSIE")> 0) & (parseint (navigator. appversion) >=4) {<br/> isie = true; <br/>}< br/> If (navigator. useragent. indexof ("Firefox")> 0) {<br/> isff = true; <br/>}< br/> If (navigator. useragent. indexof ("safari")> 0) {<br/> Issa = true; <br/>}</P> <p> // function: control Function input number <br/> func Tion onlynumber (e) {<br/> var key; <br/> ikeycode = Window. event? E. keycode: E. Which; <br/> If (! (Ikeycode> = 48) & (ikeycode <= 57) | (ikeycode = 13) | (ikeycode = 46) | (ikeycode = 45) | (ikeycode = 37) | (ikeycode = 39) | (ikeycode = 8 ))) {<br/> If (isie) {<br/> E. returnvalue = false; <br/>}else {<br/> E. preventdefault (); <br/>}</P> <p> // text box: <input type = "text" maxlength = "8" class = "input" name = "txtname" onkeypress = "Return onlynumber (event)" style = "ime-mode: dis Abled "size =" 25 "/> <br/>/* <br/> prohibit the submission of non-decimal or non-integer data. Three steps are required: <br/> 1. text Box event onkeypress = "Return onlynumber (event)" <br/> 2. text Box style = "ime-mode: Disabled" <br/> 3. add <br/> If (validatenumber ('txtname') {<br/> document. form1.submit (); <br/>}< br/> */<br/> // if a non-number is included, false is returned. Allowed decimal point <br/> function validatenumber () {<br/> var Len = arguments. length; <br/> var flag = true; <br/> for (VAR I = 0; I <arguments. length; I ++) {<br/> flag = numericcheck (arguments [I]); <br/>}< br/> return flag; <br/>}</P> <p> // function: only numbers can be entered, and a prompt is displayed for several unacceptable characters. <br/> function numericcheck (parameter) {<br/> var El = document. getelementbyid (parameter); <br/> NR1 = document. getelementbyid (parameter ). value; <br/> Flg = 0; <br/> STR = ""; <br/> SPC = ""; <br/> arw = ""; <br/> for (VAR I = 0; I <nr1.length; I ++) {<br/> CMP = ". 0123456789 "; <br/> TST = nr1.substring (I, I + 1); <br/> If (CMP. indexof (TST) <0) {<br/> flg ++; <br/> STR + = "" + TST; <br/> SPC + = TST; <br/> arw + = "^"; <br/>}else {<br/> arw + = "_"; <br/>}< br/> If (flg! = 0) {<br/> If (SPC. indexof ("")>-1) {<br/> STR + = "and space"; <br/>}< br/> var prevnode = el. parentnode. previussibling. innertext; <br/> alert (prevnode + "only numbers are allowed, and" + flg + "unacceptable characters/N" are found); <br/> el. select (); <br/> el. focus (); <br/> return false; <br/>} else {<br/> return true; <br/>}</P> <p> // determines whether the date is valid and can effectively verify the leap year. Supported date formats include: 2009-01-01, 2009/01/01 <br/> // parameter: datevalue <br/> function isdate (datevalue) {<B R/> var RegEx = new Regexp ("^ (? :(? :( [0-9] {4} (-| /)(? :(?: 0? [1, 3-9] | 1 [0-2]) (-| /)(?: 29 | 30) | ((?: 0? [13578] | 1 [02]) (-|/) 31) | ([0-9] {4} (-| /)(?: 0? [1-9] | 1 [0-2]) (-| /)(?: 0? [1-9] | 1 // d | 2 [0-8]) | (((? :( // D (?: 0 [48] | [2468] [048] | [13579] [26]) | (?: 0 [48] 00 | [2468] [048] 00 | [13579] [26] 00) (-|/) 0? 2 (-|/) 29) $ "); <br/> If (! RegEx. test (datevalue) {<br/> return false; <br/>} else {<br/> return true; <br/>}</P> <p> // comparison date. Currently, only the year-month-day format is supported. If senddate is later than sbegindate, returns true, <br/> // parameter: sbegindate <br/> // senddate <br/> function comparedate (sbegindate, senddate) {<br/> var strdt1 = sbegindate. replace ("-", "/"); <br/> var strdt2 = senddate. replace ("-", "/"); <br/> var dt1 = new date (date. parse (strdt1); <br/> var dt2 = new dat E (date. parse (strdt2); <br/> If (dt1 <= dt2) {<br/> return true; <br/>} else {<br/> return false; <br/>}</P> <p> // ============= verify the function end </P> <p> // string operation function <br/> string. prototype. trim = function () {<br/> return this. replace (/(^/S *) | (/S * $)/g, ""); <br/>}; <br/> string. prototype. ltrim = function () {<br/> return this. replace (/(^/S *)/g, ""); <br/>}; <br/> string. prototype. rtrim = function () {<br/> retu Rn this. replace (/S * $)/g, ""); <br/>}; </P> <p> // function: delete spaces between the left and right sides <br/> // parameter: Str, string to be processed <br/> function trim (STR) {<br/> return Str. replace (/(^/S *) | (/S * $)/g, ""); <br/>}</P> <p> // role: delete the left space <br/> // parameter: Str, string to be processed <br/> function ltrim (STR) {<br/> return Str. replace (/(^/S *)/g, ""); <br/>}</P> <p> // function: delete spaces on the right <br/> // parameter: Str, string to be processed <br/> function rtrim (STR) {<br/> return Str. replace (/S * $)/g, ""); <br/>}</P> <p>/ /Purpose: remove the Left and Right spaces and determine whether the length of the value is 0. If it is true, false if it is greater than 0 <br/> // parameter: value <br/> function ifvaluelengthiszero (value) {<br/> var v = trim (value); <br/> If (v. length <1) {<br/> return true; <br/>}< br/> return false; <br/>}</P> <p> // function: string operation function, digital verification <br/> // example: <input type = "text" name = "code" size = "10" maxlength = "6" onkeypress = "javascript: numinputonly ();" <br/> function numinputonly () {<br/> If (event. keycode> 57 | event. Keycode <48) {<br/> event. keycode = 0; <br/>}</P> <p> // determines whether it is an input integer. <br/> // parameter: S, input string <br/> function isint (s) {<br/> If (S. value = "") {<br/> return true; <br/>}< br/> var chk = parseint (S. value, 10); <br/> If (chk! = S. Value | chk <0) {<br/> alert ("this field should be a positive integer! "); <Br/> S. focus (); <br/> S. select (); <br/> return false; <br/>}< br/> return true; <br/>}</P> <p> // function: floating Point number input judgment <br/> // parameter: OBJ input parameter <br/> function isfloat (OBJ) {<br/> If (obj. value = "") {<br/> return true; <br/>}< br/> var chk = parsefloat (obj. value); <br/> If (chk! = Obj. Value) {<br/> alert ("this field should be an integer or decimal number! "); <Br/> obj. focus (); <br/> obj. select (); <br/> return false; <br/>}< br/> return true; <br/>}</P> <p> // function: obtain the string length <br/> // parameter: value, input string <br/> function strlen (value) {<br/> var STR, num = 0; <br/> for (VAR I = 0; I <value. length; I ++) {<br/> STR = value. substring (I, I + 1); <br/> If (STR <= "~ ") {<Br/> num + = 1; <br/>}else {<br/> num + = 2; <br/>}< br/> return num; <br/>}</P> <p> // minimum length (cannot be blank) <br/> // parameter: value, input string <br/> function vminlength (OBJ, minlength) {<br/> If (TRIM (obj. value ). length <minlength) {<br/> obj. focus (); <br/> obj. select (); <br/> return false; <br/>}< br/> return true; <br/>}</P> <p> // function: maximum length (cannot be blank) <br/> // parameter: value, input string <br/> function vmaxlength (OBJ, maxlength) {<br /> If (TRIM (obj. value ). length> maxlength) {<br/> obj. focus (); <br/> obj. select (); <br/> return false; <br/>}< br/> return true; <br/>}</P> <p> // function: judge whether the input exceeds the character length set by the database <br/> // parameter: Str, field on the page <br/> // validstrlength, database length <br/> // strname, indicating the field name <br/> // call guide: <br/>/* If (! Truelength (vcjlzdbdh. value, 50, "certificate number") {<br/> vcjlzdbdh. focus (); <br/> return (false); <br/>}< br/> If the length is exceeded, "the length of the certificate number you entered exceeds the maximum allowed value." <Br/> */<br/> function truelength (STR, validstrlength, strname) {<br/> var R; <br/> var I; <br/> var COUNT = 0; <br/> var ret; <br/> for (I = 0; I <Str. length; I ++) {<br/> r = Str. charcodeat (I, 1); <br/> If (r> 255) {<br/> COUNT = count + 2; <br/>}else {<br/> COUNT = count + 1; <br/>}< br/> If (count> validstrlength) {<br/> alert ("the length of your input" + strname + "exceeds the maximum allowed value. "); <Br/> ret = false; <br/>}else {<br/> ret = true; <br/>}< br/> return ret; <br/>}</P> <p>