JavaScript common functions_javascript skills

Javascript functions can be divided into five categories: · Regular functions · Array functions · Date functions · Mathematical functions · String functions 1. Regular functions javascript regular functions include the following 9 functions: (1) alert function: displays a warning dialog box, including an OK button. (2)confirm function: Display a confirmation dialog box, including OK and Cancel buttons. (3)escape function: Convert characters into Unicode codes. (4) eval function: calculates the result of an expression. (5) isNaN function: Test whether (true) or not (false) is not a number. (6)parseFloat function: Convert a string into dotted digital form. (7)parseInt function: Convert the string into integer digital form (the decimal system can be specified). (8)prompt function: Display an input dialog box, prompting to wait for user input. For example: alert("Input error"); prompt("Please enter your name", "Name" ; 2. Array function JavaScript array function includes the following 4 functions: (1) join function: convert and connect all elements in the array into a string. Example: Function JoinDemo() var a, b; a = new Array(0,1,2,3,4); b = a.join(" -");//Separator Return(b);//Returned b=="0-1-2-3-4" } (2)length function: Returns the array length. Example: function LengthDemo() var a, l; a = new Array(0,1,2,3,4); l = a.length; return(l);//l==5 } (3)reverse function: Reverse the order of array elements. Example: Function ReverseDemo() { var a, l; a = new Array(0,1,2,3,4); l = a.reverse() ; return(l); } (4) Sort function: Reorder array elements. Example: Function SortDemo() { var a, l; a = new Array("X","y","d", "Z", "v"," m","r"); l = a.sort(); return(l);

(1) getDate function: Returns the "day" part of the date, with values ranging from 1 to 31. Example: Function DateDemo() { var d, s = "Today's date is: "; d = new Date(); s = (d.getMonth() 1 ) "/"; s = d.getDate() "/"; s = d.getYear(); return(s); } (2)getDay function : Returns the day of the week, the value is 0~6, where 0 means Sunday, 1 means Monday,..., 6 means Saturday. Example: Function DateDemo() { var d, day, x, s = "Today is: "; var x = new Array("Sunday", "Monday", "Tuesday "); var x = x.concat("Wednesday", "Thursday", "Friday"); var x = x.concat("Saturday"); d = new Date() ; day = d.getDay(); return(s = x[day]); } (3) getHouse function: Return the "hour" part of the date, the value is 0~ twenty three. example. Function TimeDemo() { var d, s = "The current local time is: "; var c = ":"; d = new Date(); s = d.getHours() c; s = d.getMinutes() c; s = d.getSeconds() c; s = d.getMilliseconds(); return( s); } (4) getMinutes function: Returns the "minutes" part of the date, with a value of 0 to 59. See the example above. (5) getMonth function: Returns the "month" part of the date, with a value of 0 to 11. Among them, 0 represents January, 2 represents March, ..., and 11 represents December. See previous example. (6) getSeconds function: Returns the "seconds" part of the date, the value is 0~59. See previous example. (7)getTime function: Returns the system time. Function GetTimeTest() { var d, s, t; var MinMilli = 1000 * 60; var HrMilli = MinMilli * 60; ; d = new Date(); t = d.getTime(); /70"; return(s); } (8) getTimezoneOffset function: Returns the time difference in this region (the regional time difference between local time and GMT Greenwich Mean Time), in minutes. function TZDemo() { var d, tz, s = "The current local time is "; d = new Date(); tz = d.getTimezoneOffset(); if (tz s += tz / 60 + " hours before GMT"; else if (tz == 0) s += "GMT"; else s += tz / 60 + " hours after GMT"; return(s); } (9)getYear函数：返回日期的"年"部分。返回值以1900年为基数，例如1999年为99。前面有例子。 (10)parse函数：返回从1970年1月1日零时整算起的毫秒数(当地时间)。 function GetTimeTest(testdate) { var d, s, t; var MinMilli = 1000 * 60; var HrMilli = MinMilli * 60; var DyMilli = HrMilli * 24; d = new Date(); t = Date.parse(testdate); s = "There are " s += Math.round(Math.abs(t / DyMilli)) + " days " s += "between " + testdate + " and 1/1/70"; return(s); } (11)setDate函数：设定日期的"日"部分，值为0～31。 (12)setHours函数：设定日期的"小时"部分，值为0～23。 (13)setMinutes函数：设定日期的"分钟"部分，值为0～59。 (14)setMonth函数：设定日期的"月"部分，值为0～11。其中0表示1月，...，11表示12月。 (15)setSeconds函数：设定日期的"秒"部分，值为0～59。 (16)setTime函数：设定时间。时间数值为1970年1月1日零时整算起的毫秒数。 (17)setYear函数：设定日期的"年"部分。 (18)toGMTString函数：转换日期成为字符串，为GMT格林威治标准时间。 (19)setLocaleString函数：转换日期成为字符串，为当地时间。 (20)UTC函数：返回从1970年1月1日零时整算起的毫秒数，以GMT格林威治标准时间计算。 4.数学函数 javascript数学函数其实就是Math对象，它包括属性和函数(或称方法)两部分。其中，属性主要有下列内容。 Math.e:e(自然对数)、Math.LN2（2的自然对数)、Math.LN10(10的自然对数)、Math.LOG2E(e的对数，底数为2)、

Math.LOG10E(e的对数，底数为10)、Math.PI(π)、Math.SQRT1_2(1/2的平方根值)、Math.SQRT2(2的平方根值)。 函数有以下18个： (1)abs函数：即Math.abs(以下同)，返回一个数字的绝对值。 (2)acos函数：返回一个数字的反余弦值，结果为0～π弧度(radians)。 (3)asin函数：返回一个数字的反正弦值，结果为-π/2～π/2弧度。 (4)atan函数：返回一个数字的反正切值，结果为-π/2～π/2弧度。 (5)atan2函数：返回一个坐标的极坐标角度值。 (6)ceil函数：返回一个数字的最小整数值(大于或等于)。 (7)cos函数：返回一个数字的余弦值，结果为-1～1。 (8)exp函数：返回e(自然对数)的乘方值。 (9)floor函数：返回一个数字的最大整数值(小于或等于)。 (10)log函数：自然对数函数，返回一个数字的自然对数(e)值。 (11)max函数：返回两个数的最大值。 (12)min函数：返回两个数的最小值。 (13)pow函数：返回一个数字的乘方值。 (14)random函数：返回一个0～1的随机数值。 (15)round函数：返回一个数字的四舍五入值，类型是整数。 (16)sin函数：返回一个数字的正弦值，结果为-1～1。 (17)sqrt函数：返回一个数字的平方根值。 (18)tan函数：返回一个数字的正切值。 5.字符串函数 javascript字符串函数完成对字符串的字体大小、颜色、长度和查找等操作，共包括以下20个函数： (1)anchor函数：产生一个链接点(anchor)以作超级链接用。anchor函数设定的链接点的名称，另一个函数link设定的URL地址。 (2)big函数：将字体加到一号，与...标签结果相同。 (3)blink函数：使字符串闪烁，与...标签结果相同。 (4)bold函数：使字体加粗，与...标签结果相同。 (5)charAt函数：返回字符串中指定的某个字符。 (6)fixed函数：将字体设定为固定宽度字体，与...标签结果相同。 (7)fontcolor函数：设定字体颜色，与标签结果相同。 (8)fontsize函数：设定字体大小，与标签结果相同。 (9)indexOf函数：返回字符串中第一个查找到的下标index，从左边开始查找。 (10)italics函数：使字体成为斜体字，与...标签结果相同。 (11)lastIndexOf函数：返回字符串中第一个查找到的下标index，从右边开始查找。 (12)length函数：返回字符串的长度。(不用带括号) (13)link函数：产生一个超级链接，相当于设定的URL地址。 (14)small函数：将字体减小一号，与...标签结果相同。 (15)strike函数：在文本的中间加一条横线，与...标签结果相同。 (16)sub函数：显示字符串为下标字(subscript)。 (17)substring函数：返回字符串中指定的几个字符。 (18)sup函数：显示字符串为上标字(superscript)。 (19)toLowerCase函数：将字符串转换为小写。 (20)toUpperCase函数：将字符串转换为大写。

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