JS递归函数（菲波那切数列）

实例解析：

一组数字:0 1 1 2 3 5 8 13 0 1 2 3 4 5 6 7　　sl(0)=0;　　sl(1)=1;　　sl(2)=sl(0)+sl(1);　　sl(3)=sl(1)+sl(2);　　function sl(i){　　　　if(i==0){　　　　　return 0;}else if(i==1){　　　　　return 1;}else{　　　　　return sl(i-1)+sl(i-2);}}

　　正则表达式检验

//校验是否全由数字组成function isDigit(s){var patrn=/^[0-9]{1,20}$/;if (!patrn.exec(s)) return falsereturn true}//校验登录名：只能输入5-20个以字母开头、可带数字、“_”、“.”的字串function isRegisterUserName(s){var patrn=/^[a-zA-Z]{1}([a-zA-Z0-9]|[._]){4,19}$/;if (!patrn.exec(s)) return falsereturn true}//校验用户姓名：只能输入1-30个以字母开头的字串function isTrueName(s){var patrn=/^[a-zA-Z]{1,30}$/;if (!patrn.exec(s)) return falsereturn true}//校验密码：只能输入6-20个字母、数字、下划线function isPasswd(s){var patrn=/^(\w){6,20}$/;if (!patrn.exec(s)) return falsereturn true}//校验普通电话、传真号码：可以“+”开头，除数字外，可含有“-”function isTel(s){//var patrn=/^[+]{0,1}(\d){1,3}[ ]?([-]?(\d){1,12})+$/;var patrn=/^[+]{0,1}(\d){1,3}[ ]?([-]?((\d)|[ ]){1,12})+$/;if (!patrn.exec(s)) return falsereturn true}//校验手机号码：必须以数字开头，除数字外，可含有“-”function isMobil(s){var patrn=/^[+]{0,1}(\d){1,3}[ ]?([-]?((\d)|[ ]){1,12})+$/;if (!patrn.exec(s)) return falsereturn true}//校验邮政编码function isPostalCode(s){//var patrn=/^[a-zA-Z0-9]{3,12}$/;var patrn=/^[a-zA-Z0-9 ]{3,12}$/;if (!patrn.exec(s)) return falsereturn true}//校验搜索关键字function isSearch(s){var patrn=/^[^`~!@#$%^&*()+=|\\\][\]\{\}:;\'\,.<>/?]{1}[^`~!@$%^&()+=|\\\][\]\{\}:;\'\,.<>?]{0,19}$/;if (!patrn.exec(s)) return falsereturn true}function isIP(s) //by zergling{var patrn=/^[0-9.]{1,20}$/;if (!patrn.exec(s)) return falsereturn true}* FUNCTION: isBetween* PARAMETERS: val AS any value* lo AS Lower limit to check* hi AS Higher limit to check* CALLS: NOTHING* RETURNS: TRUE if val is between lo and hi both inclusive, otherwise false.function isBetween (val, lo, hi) {if ((val < lo) || (val > hi)) { return(false); }else { return(true); }}* FUNCTION: isDate checks a valid date* PARAMETERS: theStr AS String* CALLS: isBetween, isInt* RETURNS: TRUE if theStr is a valid date otherwise false.function isDate (theStr) {var the1st = theStr.indexOf('-');var the2nd = theStr.lastIndexOf('-');if (the1st == the2nd) { return(false); }else {var y = theStr.substring(0,the1st);var m = theStr.substring(the1st+1,the2nd);var d = theStr.substring(the2nd+1,theStr.length);var maxDays = 31;if (isInt(m)==false || isInt(d)==false || isInt(y)==false) {return(false); }else if (y.length < 4) { return(false); }else if (!isBetween (m, 1, 12)) { return(false); }else if (m==4 || m==6 || m==9 || m==11) maxDays = 30;else if (m==2) {if (y % 4 > 0) maxDays = 28;else if (y % 100 == 0 && y % 400 > 0) maxDays = 28;else maxDays = 29;}if (isBetween(d, 1, maxDays) == false) { return(false); }else { return(true); }}}* FUNCTION: isEuDate checks a valid date in British format* PARAMETERS: theStr AS String* CALLS: isBetween, isInt* RETURNS: TRUE if theStr is a valid date otherwise false.function isEuDate (theStr) {if (isBetween(theStr.length, 8, 10) == false) { return(false); }else {var the1st = theStr.indexOf('/');var the2nd = theStr.lastIndexOf('/');if (the1st == the2nd) { return(false); }else {var m = theStr.substring(the1st+1,the2nd);var d = theStr.substring(0,the1st);var y = theStr.substring(the2nd+1,theStr.length);var maxDays = 31;if (isInt(m)==false || isInt(d)==false || isInt(y)==false) {return(false); }else if (y.length < 4) { return(false); }else if (isBetween (m, 1, 12) == false) { return(false); }else if (m==4 || m==6 || m==9 || m==11) maxDays = 30;else if (m==2) {if (y % 4 > 0) maxDays = 28;else if (y % 100 == 0 && y % 400 > 0) maxDays = 28;else maxDays = 29;}if (isBetween(d, 1, maxDays) == false) { return(false); }else { return(true); }}}}* FUNCTION: Compare Date! Which is the latest!* PARAMETERS: lessDate,moreDate AS String* CALLS: isDate,isBetween* RETURNS: TRUE if lessDate<moreDatefunction isComdate (lessDate , moreDate){if (!isDate(lessDate)) { return(false);}if (!isDate(moreDate)) { return(false);}var less1st = lessDate.indexOf('-');var less2nd = lessDate.lastIndexOf('-');var more1st = moreDate.indexOf('-');var more2nd = moreDate.lastIndexOf('-');var lessy = lessDate.substring(0,less1st);var lessm = lessDate.substring(less1st+1,less2nd);var lessd = lessDate.substring(less2nd+1,lessDate.length);var morey = moreDate.substring(0,more1st);var morem = moreDate.substring(more1st+1,more2nd);var mored = moreDate.substring(more2nd+1,moreDate.length);var Date1 = new Date(lessy,lessm,lessd);var Date2 = new Date(morey,morem,mored);if (Date1>Date2) { return(false);}return(true);}* FUNCTION isEmpty checks if the parameter is empty or null* PARAMETER str AS Stringfunction isEmpty (str) {if ((str==null)||(str.length==0)) return true;else return(false);}* FUNCTION: isInt* PARAMETER: theStr AS String* RETURNS: TRUE if the passed parameter is an integer, otherwise FALSE* CALLS: isDigitfunction isInt (theStr) {var flag = true;if (isEmpty(theStr)) { flag=false; }else{ for (var i=0; i<theStr.length; i++) {if (isDigit(theStr.substring(i,i+1)) == false) {flag = false; break;}}}return(flag);}* FUNCTION: isReal* PARAMETER: heStr AS StringdecLen AS Integer (how many digits after period)* RETURNS: TRUE if theStr is a float, otherwise FALSE* CALLS: isIntfunction isReal (theStr, decLen) {var dot1st = theStr.indexOf('.');var dot2nd = theStr.lastIndexOf('.');var OK = true;if (isEmpty(theStr)) return false;if (dot1st == -1) {if (!isInt(theStr)) return(false);else return(true);}else if (dot1st != dot2nd) return (false);else if (dot1st==0) return (false);else {var intPart = theStr.substring(0, dot1st);var decPart = theStr.substring(dot2nd+1);if (decPart.length > decLen) return(false);else if (!isInt(intPart) || !isInt(decPart)) return (false);else if (isEmpty(decPart)) return (false);else return(true);}}* FUNCTION: isEmail* PARAMETER: String (Email Address)* RETURNS: TRUE if the String is a valid Email address* FALSE if the passed string is not a valid Email Address* EMAIL FORMAT: AnyName@EmailServer e.g; webmaster@hotmail.com* @ sign can appear only once in the email address.function isEmail (theStr) {var atIndex = theStr.indexOf('@');var dotIndex = theStr.indexOf('.', atIndex);var flag = true;theSub = theStr.substring(0, dotIndex+1)if ((atIndex < 1)||(atIndex != theStr.lastIndexOf('@'))||(dotIndex < atIndex + 2)||(theStr.length <= theSub.length)){ return(false); }else { return(true); }}* FUNCTION: newWindow* PARAMETERS: doc -> Document to open in the new windowhite -> Height of the new windowwide -> Width of the new windowbars -> 1-Scroll bars = YES 0-Scroll Bars = NOresize -> 1-Resizable = YES 0-Resizable = NO* CALLS: NONE* RETURNS: New window instancefunction newWindow (doc, hite, wide, bars, resize) {var winNew="_blank";var opt="toolbar=0,location=0,directories=0,status=0,menubar=0,";opt+=("scrollbars="+bars+",");opt+=("resizable="+resize+",");opt+=("width="+wide+",");opt+=("height="+hite);winHandle=window.open(doc,winNew,opt);return;}* FUNCTION: DecimalFormat* PARAMETERS: paramValue -> Field value* CALLS: NONE* RETURNS: Formated stringfunction DecimalFormat (paramValue) {var intPart = parseInt(paramValue);var decPart =parseFloat(paramValue) - intPart;str = "";if ((decPart == 0) || (decPart == null)) str += (intPart + ".00");else str += (intPart + decPart);return (str);}

正则表达式应用

"^\\d+$"　　//非负整数（正整数 + 0） "^[0-9]*[1-9][0-9]*$"　　//正整数 "^((-\\d+)|(0+))$"　　//非正整数（负整数 + 0） "^-[0-9]*[1-9][0-9]*$"　　//负整数 "^-?\\d+$"　　　　//整数 "^\\d+(\\.\\d+)?$"　　//非负浮点数（正浮点数 + 0） "^(([0-9]+\\.[0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\\.[0-9]+)|([0-9]*[1-9][0-9]*))$"　　//正浮点数 "^((-\\d+(\\.\\d+)?)|(0+(\\.0+)?))$"　　//非正浮点数（负浮点数 + 0） "^(-(([0-9]+\\.[0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\\.[0-9]+)|([0-9]*[1-9][0-9]*)))$"　　//负浮点数 "^(-?\\d+)(\\.\\d+)?$"　　//浮点数 "^[A-Za-z]+$"　　//由26个英文字母组成的字符串 "^[A-Z]+$"　　//由26个英文字母的大写组成的字符串 "^[a-z]+$"　　//由26个英文字母的小写组成的字符串 "^[A-Za-z0-9]+$"　　//由数字和26个英文字母组成的字符串 "^\\w+$"　　//由数字、26个英文字母或者下划线组成的字符串 "^[\\w-]+(\\.[\\w-]+)*@[\\w-]+(\\.[\\w-]+)+$"　　　　//email地址 "^[a-zA-z]+://(\\w+(-\\w+)*)(\\.(\\w+(-\\w+)*))*(\\?\\S*)?$"　　//url

递归函数应用

总结

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