Javascript 简明教程
JavaScript Built-in Functions
Number Methods
Number 对象仅包含属于每个对象定义一部分的默认方法。
The Number object contains only the default methods that are part of every object’s definition.
Sr.No. |
Method & Description |
1 |
constructor()Returns the function that created this object’s instance. By default this is the Number object. |
2 |
toExponential()Forces a number to display in exponential notation, even if the number is in the range in which JavaScript normally uses standard notation. |
3 |
toFixed()Formats a number with a specific number of digits to the right of the decimal. |
4 |
toLocaleString()Returns a string value version of the current number in a format that may vary according to a browser’s locale settings. |
5 |
toPrecision()Defines how many total digits (including digits to the left and right of the decimal) to display of a number. |
6 |
toString()Returns the string representation of the number’s value. |
7 |
valueOf()Returns the number’s value. |
Boolean Methods
以下是每种方法及其说明的列表。
Here is a list of each method and its description.
Sr.No. |
Method & Description |
1 |
toSource()Returns a string containing the source of the Boolean object; you can use this string to create an equivalent object. |
2 |
toString()Returns a string of either "true" or "false" depending upon the value of the object. |
3 |
valueOf()Returns the primitive value of the Boolean object. |
String Methods
以下是每种方法及其说明的列表。
Here is a list of each method and its description.
Sr.No. |
Method & Description |
1 |
charAt()Returns the character at the specified index. |
2 |
charCodeAt()Returns a number indicating the Unicode value of the character at the given index. |
3 |
concat()Combines the text of two strings and returns a new string. |
4 |
indexOf()Returns the index within the calling String object of the first occurrence of the specified value, or -1 if not found. |
5 |
lastIndexOf()Returns the index within the calling String object of the last occurrence of the specified value, or -1 if not found. |
6 |
localeCompare()Returns a number indicating whether a reference string comes before or after or is the same as the given string in sort order. |
7 |
length()Returns the length of the string. |
8 |
match()Used to match a regular expression against a string. |
9 |
replace()Used to find a match between a regular expression and a string, and to replace the matched substring with a new substring. |
10 |
search()Executes the search for a match between a regular expression and a specified string. |
11 |
slice()Extracts a section of a string and returns a new string. |
12 |
split()Splits a String object into an array of strings by separating the string into substrings. |
13 |
substr()Returns the characters in a string beginning at the specified location through the specified number of characters. |
14 |
substring()Returns the characters in a string between two indexes into the string. |
15 |
toLocaleLowerCase()The characters within a string are converted to lower case while respecting the current locale. |
16 |
toLocaleUpperCase()The characters within a string are converted to upper case while respecting the current locale. |
17 |
toLowerCase()Returns the calling string value converted to lower case. |
18 |
toString()Returns a string representing the specified object. |
19 |
toUpperCase()Returns the calling string value converted to uppercase. |
20 |
valueOf()Returns the primitive value of the specified object. |
String HTML wrappers
以下是每种方法的列表,它返回包裹在适当 HTML 标记内的字符串的副本。
Here is a list of each method which returns a copy of the string wrapped inside the appropriate HTML tag.
Sr.No. |
Method & Description |
1 |
anchor()Creates an HTML anchor that is used as a hypertext target. |
2 |
big()Creates a string to be displayed in a big font as if it were in a <big> tag. |
3 |
blink()Creates a string to blink as if it were in a <blink> tag. |
4 |
bold()Creates a string to be displayed as bold as if it were in a <b> tag. |
5 |
fixed()Causes a string to be displayed in fixed-pitch font as if it were in a <tt> tag |
6 |
fontcolor()Causes a string to be displayed in the specified color as if it were in a <font color="color"> tag. |
7 |
fontsize()Causes a string to be displayed in the specified font size as if it were in a <font size="size"> tag. |
8 |
italics()Causes a string to be italic, as if it were in an <i> tag. |
9 |
link()Creates an HTML hypertext link that requests another URL. |
10 |
small()Causes a string to be displayed in a small font, as if it were in a <small> tag. |
11 |
strike()Causes a string to be displayed as struck-out text, as if it were in a <strike> tag. |
12 |
sub()Causes a string to be displayed as a subscript, as if it were in a <sub> tag |
13 |
sup()Causes a string to be displayed as a superscript, as if it were in a <sup> tag |
Array Methods
以下是每种方法及其说明的列表。
Here is a list of each method and its description.
Sr.No. |
Method & Description |
1 |
concat()Returns a new array comprised of this array joined with other array(s) and/or value(s). |
2 |
every()Returns true if every element in this array satisfies the provided testing function. |
3 |
filter()Creates a new array with all of the elements of this array for which the provided filtering function returns true. |
4 |
forEach()Calls a function for each element in the array. |
5 |
indexOf()Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found. |
6 |
join()Joins all elements of an array into a string. |
7 |
lastIndexOf()Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found. |
8 |
map()Creates a new array with the results of calling a provided function on every element in this array. |
9 |
pop()Removes the last element from an array and returns that element. |
10 |
push()Adds one or more elements to the end of an array and returns the new length of the array. |
11 |
reduce()Apply a function simultaneously against two values of the array (from left-to-right) as to reduce it to a single value. |
12 |
reduceRight()Apply a function simultaneously against two values of the array (from right-to-left) as to reduce it to a single value. |
13 |
reverse()Reverses the order of the elements of an array — the first becomes the last, and the last becomes the first. |
14 |
shift()Removes the first element from an array and returns that element. |
15 |
slice()Extracts a section of an array and returns a new array. |
16 |
some()Returns true if at least one element in this array satisfies the provided testing function. |
17 |
toSource()Represents the source code of an object |
18 |
sort()Sorts the elements of an array. |
19 |
splice()Adds and/or removes elements from an array. |
20 |
toString()Returns a string representing the array and its elements. |
21 |
unshift()Adds one or more elements to the front of an array and returns the new length of the array. |
Date Methods
以下是每种方法及其说明的列表。
Here is a list of each method and its description.
Sr.No. |
Method & Description |
1 |
Date()Returns today’s date and time |
2 |
getDate()Returns the day of the month for the specified date according to local time. |
3 |
getDay()Returns the day of the week for the specified date according to local time. |
4 |
getFullYear()Returns the year of the specified date according to local time. |
5 |
getHours()Returns the hour in the specified date according to local time. |
6 |
getMilliseconds()Returns the milliseconds in the specified date according to local time. |
7 |
getMinutes()Returns the minutes in the specified date according to local time. |
8 |
getMonth()Returns the month in the specified date according to local time. |
9 |
getSeconds()Returns the seconds in the specified date according to local time. |
10 |
getTime()Returns the numeric value of the specified date as the number of milliseconds since January 1, 1970, 00:00:00 UTC. |
11 |
getTimezoneOffset()Returns the time-zone offset in minutes for the current locale. |
12 |
getUTCDate()Returns the day (date) of the month in the specified date according to universal time. |
13 |
getUTCDay()Returns the day of the week in the specified date according to universal time. |
14 |
getUTCFullYear()Returns the year in the specified date according to universal time. |
15 |
getUTCHours()Returns the hours in the specified date according to universal time. |
16 |
getUTCMilliseconds()Returns the milliseconds in the specified date according to universal time. |
17 |
getUTCMinutes()Returns the minutes in the specified date according to universal time. |
18 |
getUTCMonth()Returns the month in the specified date according to universal time. |
19 |
getUTCSeconds()Returns the seconds in the specified date according to universal time. |
20 |
getYear()Deprecated - Returns the year in the specified date according to local time. Use getFullYear instead. |
21 |
setDate()Sets the day of the month for a specified date according to local time. |
22 |
setFullYear()Sets the full year for a specified date according to local time. |
23 |
setHours()Sets the hours for a specified date according to local time. |
24 |
setMilliseconds()Sets the milliseconds for a specified date according to local time. |
25 |
setMinutes()Sets the minutes for a specified date according to local time. |
26 |
setMonth()Sets the month for a specified date according to local time. |
27 |
setSeconds()Sets the seconds for a specified date according to local time. |
28 |
setTime()Sets the Date object to the time represented by a number of milliseconds since January 1, 1970, 00:00:00 UTC. |
29 |
setUTCDate()Sets the day of the month for a specified date according to universal time. |
30 |
setUTCFullYear()Sets the full year for a specified date according to universal time. |
31 |
setUTCHours()Sets the hour for a specified date according to universal time. |
32 |
setUTCMilliseconds()Sets the milliseconds for a specified date according to universal time. |
33 |
setUTCMinutes()Sets the minutes for a specified date according to universal time. |
34 |
setUTCMonth()Sets the month for a specified date according to universal time. |
35 |
setUTCSeconds()Sets the seconds for a specified date according to universal time. |
36 |
setYear()*Deprecated - * Sets the year for a specified date according to local time. Use setFullYear instead. |
37 |
toDateString()Returns the "date" portion of the Date as a human-readable string. |
38 |
toGMTString()*Deprecated - * Converts a date to a string, using the Internet GMT conventions. Use toUTCString instead. |
39 |
toLocaleDateString()Returns the "date" portion of the Date as a string, using the current locale’s conventions. |
40 |
toLocaleFormat()Converts a date to a string, using a format string. |
41 |
toLocaleString()Converts a date to a string, using the current locale’s conventions. |
42 |
toLocaleTimeString()Returns the "time" portion of the Date as a string, using the current locale’s conventions. |
43 |
toSource()Returns a string representing the source for an equivalent Date object; you can use this value to create a new object. |
44 |
toString()Returns a string representing the specified Date object. |
45 |
toTimeString()Returns the "time" portion of the Date as a human-readable string. |
46 |
toUTCString()Converts a date to a string, using the universal time convention. |
47 |
valueOf()Returns the primitive value of a Date object. |
Date Static Methods
除了前面列出的许多实例方法之外,Date 对象还定义了两种静态方法。这些方法通过 Date( ) 构造函数本身调用:
In addition to the many instance methods listed previously, the Date object also defines two static methods. These methods are invoked through the Date( ) constructor itself −
Sr.No. |
Method & Description |
1 |
Date.parse( )Parses a string representation of a date and time and returns the internal millisecond representation of that date. |
2 |
Date.UTC( )Returns the millisecond representation of the specified UTC date and time. |
Math Methods
以下是每种方法及其说明的列表。
Here is a list of each method and its description.
Sr.No. |
Method & Description |
1 |
abs()Returns the absolute value of a number. |
2 |
acos()Returns the arccosine (in radians) of a number. |
3 |
asin()Returns the arcsine (in radians) of a number. |
4 |
atan()Returns the arctangent (in radians) of a number. |
5 |
atan2()Returns the arctangent of the quotient of its arguments. |
6 |
ceil()Returns the smallest integer greater than or equal to a number. |
7 |
cos()Returns the cosine of a number. |
8 |
exp()Returns EN, where N is the argument, and E is Euler’s constant, the base of the natural logarithm. |
9 |
floor()Returns the largest integer less than or equal to a number. |
10 |
log()Returns the natural logarithm (base E) of a number. |
11 |
max()Returns the largest of zero or more numbers. |
12 |
min()Returns the smallest of zero or more numbers. |
13 |
pow()Returns base to the exponent power, that is, base exponent. |
14 |
random()Returns a pseudo-random number between 0 and 1. |
15 |
round()Returns the value of a number rounded to the nearest integer. |
16 |
sin()Returns the sine of a number. |
17 |
sqrt()Returns the square root of a number. |
18 |
tan()Returns the tangent of a number. |
19 |
toSource()Returns the string "Math". |
RegExp Methods
以下是每种方法及其说明的列表。
Here is a list of each method and its description.
Sr.No. |
Method & Description |
1 |
exec()Executes a search for a match in its string parameter. |
2 |
test()Tests for a match in its string parameter. |
3 |
toSource()Returns an object literal representing the specified object; you can use this value to create a new object. |
4 |
toString()Returns a string representing the specified object. |