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js built-in functions are functions that come with the browser kernel and can be used directly without introducing any function library. JavaScript built-in functions can be divided into five categories: 1. Regular functions; 2. Array functions; 3. Date functions; 4. Mathematical functions; 5. String functions.
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
js built-in functions are functions that come with the browser kernel and can be used directly without introducing any function library. JavaScript built-in functions can be divided into five categories:
1, regular function
2, array function
3, date function
4, mathematical function
5. String functions
The first category: regular functions
includes 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.
Second Category: Array Function
Includes the following 4 functions:
(1)Join function: Convert and connect all elements in the array into a string.
(2)langth function: Returns the length of the array.
(3)reverse function: Reverse the order of array elements.
(4)sort function: Reorder array elements.
The third category: date function
Includes the following 20 functions:
(1)getDate function: returns the "day" part of the date, with values from 1 to 31
(2)getDay function: Returns the day of the week, the value is 0~6, where 0 means Sunday, 1 means Monday,..., 6 means Saturday
(3)getHours function: Returns the "hour" part of the date, with values ranging from 0 to 23.
(4)getMinutes function: Returns the "minutes" part of the date, the value is 0~59. See the example above.
(5)getMonth function: Returns the "month" part of the date, the value is 0~11. 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.
(8)getTimezoneOffset function: Returns the time difference in this region (the regional time difference between local time and GMT Greenwich Mean Time), in minutes.
(9)getYear function: Returns the "year" part of the date. The return value is based on 1900, for example, 1999 is 99.
(10)parse function: Returns the number of milliseconds since 0:00 on January 1, 1970 (local time).
(11)setDate function: Set the "day" part of the date, the value is 0~31.
(12)setHours function: Set the "hour" part of the date, the value is 0~23.
(13)setMinutes function: Set the "minutes" part of the date, the value is 0~59.
(14)setMonth function: Set the "month" part of the date, the value is 0~11. Among them, 0 represents January, ..., and 11 represents December.
(15)setSeconds function: Set the "seconds" part of the date, the value is 0~59.
(16)setTime function: set time. The time value is the number of milliseconds since 00:00 on January 1, 1970.
(17)setYear function: Set the "year" part of the date.
(18)toGMTString function: Convert the date into a string, which is GMT Greenwich Mean Time.
(19)setLocaleString function: Convert date into string and local time.
(20) UTC function: Returns the number of milliseconds since 0:00 on January 1, 1970, calculated in GMT Greenwich Mean Time.
Fourth Category: Mathematical Functions
There are 18 functions as follows:
(1)abs function: Math.abs (the same below), returns the absolute value of a number value.
(2) acos function: Returns the inverse cosine value of a number, and the result is 0 to π radians (radians).
(3)asin function: Returns the arcsine value of a number, and the result is -π/2~π/2 radians.
(4)atan function: Returns the arctangent value of a number, and the result is -π/2~π/2 radians.
(5)atan2 function: Returns the polar coordinate angle value of a coordinate.
(6)ceil function: Returns the smallest integer value of a number (greater than or equal to).
(7)cos function: Returns the cosine value of a number, and the result is -1~1.
(8)exp function: Returns the power value of e (natural logarithm).
(9)floor function: Returns the maximum integer value of a number (less than or equal to).
(10)log function: natural logarithm function, returns the natural logarithm (e) value of a number.
(11)max function: Returns the maximum value of two numbers.
(12)min function: Returns the minimum value of two numbers.
(13)pow function: Returns the power of a number.
(14)random function: Returns a random value between 0 and 1.
(15)round function: Returns the rounded value of a number, the type is integer.
(16) sin function: returns the sine value of a number, and the result is -1~1.
(17)sqrt function: Returns the square root value of a number.
(18)tan function: Returns the tangent value of a number.
Fifth Category: String Function
Includes the following 20 functions:
(1)anchor function: generates a link point (anchor) for use as a hyperlink. The anchor function sets the name of the link point of , and the other function link sets the URL address of .
(2)big function: Increase the font to size one, which is the same as the ... tag.
(3)blink function: Makes the string blink, which is the same as the tag result.
(4)bold function: Make the font bold, which is the same as the ... tag result.
(5)charAt function: Returns a character specified in the string.
(6)fixed function: Set the font to a fixed-width font, which is the same as the ... tag.
(7)fontcolor function: Set the font color, which is the same as the tag result.
(8)fontsize function: Set the font size, which is the same as the tag result.
(9)indexOf function: Returns the first index found in the string, starting from the left.
(10) italics function: Make the font italic, which is the same as the ... tag result.
(11)lastIndexOf function: Returns the first subscript index found in the string, starting from the right.
(12)length function: Returns the length of the string. (Without parentheses)
(13) link function: Generate a hyperlink, which is equivalent to setting the URL address of .
(14)small function: Reduce the font size by one size, which is the same as the ... tag.
(15)strike function: Add a horizontal line in the middle of the text, which is the same as the ... tag.
(16)sub function: Display the string as a subscript.
(17)substring function: Returns several characters specified in the string.
(18)sup function: Display the string as superscript.
(19)toLowerCase function: Convert the string to lowercase.
(20)toUpperCase function: Convert the string to uppercase.
[Recommended learning: javascript advanced tutorial]
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