js common functions good_basic knowledge

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:
　(9)unescape function: Decode characters encoded by the escape function.
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:

Program code
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)langth function: Returns the length of the array. Example:
　
Program code
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:
　
Program code
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:
　
Program code
function SortDemo()
　{
　var a, l;
a = new Array("X","y","d", Z", "v","m","r");
l = a.sort();
return(l);
}
3. Date function
javascript The date function includes the following 20 functions:
(1) getDate function: returns the "day" part of the date, with values ​​from 1 to 31. Example:
　
Program code
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:
　
Program code
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]); hour" part, the value is 0~23. example.
　
Program code
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);
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 the 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.
　
Program code
function GetTimeTest()
　{
　var d, s, t;
　var MinMilli = 1000 * 60; 🎜> var DyMilli = HrMilli * 24;
d = new Date();
t = d.getTime();
s = "It's been "
s = Math.round(t / DyMilli) " days since 1/1/70";
return(s);
time difference) in minutes.
　
Program code
function TZDemo()
　{
　var d, tz, s = "The current local time is ";
d = new Date();
tz = d.getTimezoneOffset();

if (the name of the link point of tz, the URL address set by another function link.
(2) big function: increase the font to size one, and ...The label result is the same. (3) Blink function: Makes the string blink, which is the same as the ... label result.
(4) Bold function: Makes the font bold, which is the same as the ... label result. .
(5) charAt function: Returns a character specified in the string. (6) Fixed function: Sets the font to a fixed-width font, the same as... tag result. 7) Fontcolor function: Set the font color, which is the same as the label result. (8) Fontsize function: Set the font size, which is the same as the label result. (9) IndexOf function: Return the first one in the string. Find the subscript index, starting from the left.
　(10)italics function: Make the font italic, the same as... tag result.
　(11)lastIndexOf function: return the first one in the string. Find the subscript index, starting from the right.
　(12)length function: Return the length of the string (without parentheses)
　(13)Link function: Generate a hyperlink, equivalent to setting.
　(14) Small function: Reduce the font size by one size, the same result as... tag.
　(15) Strike function: Add a horizontal line in the middle of the text, as... .The label result is the same.
　(16) Sub function: Display the string as a subscript (17) Substring function: Return the specified characters in the string. sup function: Display the string as superscript. (19) toLowerCase function: Convert the string to lowercase. (20) ToUpperCase function: Convert the string to uppercase.

//Check whether it is all composed of numbers

Program code
function isDigit(s)
{
var patrn=/^[0-9]{1 ,20}$/;
if (!patrn.exec(s)) return false
return true
}


//Verify login name: only 5 can be entered -20 strings starting with letters and can contain numbers, "_", "."

Program code
function isRegisterUserName(s)
{
var patrn=/^[ a-zA-Z]{1}([a-zA-Z0-9]|[._]){4,19}$/;
if (!patrn.exec(s)) return false
return true
}


//Verify user name: Only 1-30 strings starting with letters can be entered

Program code
function isTrueName( s)
{
var patrn=/^[a-zA-Z]{1,30}$/;
if (!patrn.exec(s)) return false
return true
}

//Verification password: only 6-20 letters, numbers, and underscores can be entered

Program code
function isPasswd(s)
{
var patrn=/^(w){6,20}$/;
if (!patrn.exec(s)) return false
return true
}


/ /Verify ordinary telephone and fax numbers: It can start with " ", and in addition to numbers, it can contain "-"

Program code
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 false
return true
}


//Verify mobile phone number: must start with a number. In addition to numbers, it can contain "-"

Program code
function isMobil(s)
{
var patrn=/^[ ]{0,1}(d){1,3}[ ]?([-]?((d)|[ ]){ 1,12}) $/;
if (!patrn.exec(s)) return false
return true
}

//Verify postal code

Program code
function isPostalCode(s)
{
//var patrn=/^[a-zA-Z0-9]{3,12}$/;
var patrn=/^[ a-zA-Z0-9 ]{3,12}$/;
if (!patrn.exec(s)) return false
return true
}

//Verification Search keywords

Program code
function isSearch(s)
{
var patrn=/^[^`~!@#$%^&*() =|\][ ]{}:;',./?]{1}[^`~!@$%^&() =|\][]{}:;',.?]{0, 19}$/;
if (!patrn.exec(s)) return false
return true
}


Program code
function isIP(s) // by zergling
{
var patrn=/^[0-9.]{1,20}$/;
if (!patrn.exec(s)) return false
return true
}