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Шпаргалка по JavaScript

Turing Bootcamp 30.08.2021 0

Если вы хотите создавать динамические веб-страницы, вам придется дополнить свои знания HTML и CSS пониманием JS . Этот язык сценариев считается важным в современной веб-разработке.

Шпаргалка может помочь вам быстро освежить в памяти элементы JavaScript в любое время, когда они вам понадобятся. Это удобно как для новичков, так и для экспертов.

JavaScript Arrays
concat() Join several arrays into one
copyWithin() Copy array elements within the array, to and from specified positions
indexOf() Return the primitive value of the specified object
includes() Check if an array contains the specified element
join() Combine elements of an array into a single string and return the string
entries() Return a key/value pair Array Iteration Object
every() Check if every element in an array passes a test
fill() Fill the elements in an array with a static value
filter() Create a new array with every element in an array that pass a test
find() Return the value of the first element in an array that pass a test
forEach() Call a function for each array element
from() Create an array from an object
lastIndexOf() Give the last position at which a given element appears in an array
pop() Remove the last element of an array
push() Add a new element at the end
reverse() Sort elements in descending order
reduce() Reduce the values of an array to a single value (going left-to-right)
reduceRight() Reduce the values of an array to a single value (going right-to-left)
shift() Remove the first element of an array
slice() Pull a copy of a portion of an array into a new array object
sort() Sort elements alphabetically
splice() Add elements in a specified way and position
unshift() Add a new element to the beginning

JavaScript Boolean Methods
toString() Convert a Boolean value to a string, and return the result
valueOf() Return the first position at which a given element appears in an array
toSource() Return a string representing the source code of the objec

JavaScript Arithmetic Operators
+ Addition
— Subtraction
* Multiplication
/ Division
(…) Grouping operator (operations within brackets are executed earlier than those outside)
% Modulus (remainder)
++ Increment numbers
— Decrement numbers
== Equal to
=== Equal value and equal type
!= Not equal
!== Not equal value or not equal type
> Greater than
< Lesser than >= Greater than or equal to
<= Lesser than or equal to
? Ternary operator

Logical Operators
&& Logical AND
|| Logical OR
! Logical NOT
Bitwise Operators
& AND statement
| OR statement
~ NOT
^ XOR
<< Left shift >> Right shift
>>> Zero fill right shift

Functions
alert() Output data in an alert box in the browser window
confirm() Open up a yes/no dialog and return true/false depending on user click
console.log() Write information to the browser console (good for debugging purposes)
document.write() Write directly to the HTML document
prompt() Create a dialog for user input

Global Functions
decodeURI() Decode a Uniform Resource Identifier (URI) created by encodeURI or similar
decodeURIComponent() Decode a URI component
encodeURI() Encode a URI into UTF-8
encodeURIComponent() Same but for URI components
eval() Evaluate JavaScript code represented as a string
isFinite() Determine whether a passed value is a finite number
isNaN() Determine whether a value is an illegal number
Number() Convert an object’s value to a number
parseFloat() Parse a string and return a floating point number
parseInt() Parse a string and return an integer

JavaScript Loops
for The most common way to create a loop in JavaScript
while Set up conditions under which a loop executes
do while Similar to the while loop, however, it executes at least once and performs a check at the end to see if the condition is met to execute again
break Stop and exit the cycle if certain conditions are mets
Skip parts of the cycle if certain conditions are met

Escape Characters
\’ Single quote
\» Double quote
\\ Backslash
\b Backspace
\f Form feed
\n New line
\r Carriage return
\t Horizontal tabulator
\v Vertical tabulator

JavaScript String Methods
charAt() Return a character at a specified position inside a string
charCodeAt() Give the unicode of character at that position
concat() Concatenate (join) two or more strings into one
fromCharCode() Return a string created from the specified sequence of UTF-16 code units
indexOf() Provide the position of the first occurrence of specified text within a string
lastIndexOf() Same as indexOf() but with the last occurrence, searching backwards
match() Retrieve the matches of a string against a search pattern
replace() Find and replace specified text in a string
search() Execute a search for a matching text and return its position
slice() Extract a section of a string and return it as a new string
split() Split a string object into an array of strings at a specified position
startsWith() Check whether a string begins with specified characters
substr() Similar to slice() but extracts a substring depended on a specified number of characters
substring() Similar to slice() but can’t accept negative indices
toLowerCase() Convert strings to lower case
toUpperCase() Convert strings to upper case
valueOf() Return the primitive value (that has no properties or methods) of a string object

REGULAR EXPRESSION SYNTAX

Pattern Modifiers
e Evaluate replacement
i Perform case-insensitive matching
g Perform global matching
m Perform multiple line matching
s Treat strings as single line
x Allow comments and whitespace in pattern
U Ungreedy pattern

Brackets
[abc] Find any of the characters in the brackets
[^abc] Find any character not in the brackets
[0-9] Find digit specified in the brackets
[A-z] Find any character from uppercase A to lowercase z
(a|b|c) Find any of the alternatives separated with |

Metacharacters
. Find a single character, except newline or line terminator
\w Word character
\W Non-word character
\d A digit
\D A non-digit character
\s Whitespace character
\S Non-whitespace character
\b Find a match at the beginning/end of a word
\B Find a match not at the beginning/end of a word
\u0000 NUL character
\n A new line character
\f Form feed character
\r Carriage return character
\t Tab character
\v Vertical tab character
\xxx Character specified by an octal number xxx
\xdd Latin character specified by a hexadecimal number dd
\udddd Unicode character specified by a hexadecimal number dddd

Quantifiers
n+ Match any string that contains at least one n
n* Any string that contains zero or more occurrences of n
n? Any string that contains zero or one occurrences of n
n{X} Any string that contains a sequence of X n’s
n{X,Y} Strings that contains a sequence of X to Y n’s
n{X,} Matches any string that contains a sequence of at least X n’s
n$ Any string with n at the end of it
^n String with n at the beginning of it
?=n Any string that is followed by a specific string n
?!n String that is not followed by a specific string n

Number Properties
MAX_VALUE Maximum numeric value representable in JavaScript
MIN_VALUE Smallest positive numeric value representable in JavaScript
NaN The “Not-a-Number” value
NEGATIVE_INFINITY Negative Infinity value
POSITIVE_INFINITY Positive Infinity value

Number Methods
toExponential() Return a string with a rounded number written as exponential notation
toFixed() Return string of a number with a specified number of decimals
toPrecision() Return string of a number written with a specified length
toString() Return a number as a string
valueOf() Return a number as a number

Math Properties
E Euler’s number
LN2 Natural logarithm of 2
LN10 Natural logarithm of 10
LOG2E Base 2 logarithm of E
LOG10E Base 10 logarithm of E
PI The number PI
SQRT1_2 Square root of 1/2
SQRT2 Square root of 2

Math Methods
abs(x) Return the absolute (positive) value of x
acos(x) Arccosine of x, in radians
asin(x) Arcsine of x, in radians
atan(x) Arctangent of x as a numeric value
atan2(y,x) Arctangent of the quotient of its arguments
ceil(x) Value of x rounded up to its nearest integer
cos(x) Cosine of x (x is in radians)
exp(x) Value of Ex
floor(x) Value of x rounded down to its nearest integer
log(x) Natural logarithm (base E) of x
max(x,y,z,…,n) Number with highest value
min(x,y,z,…,n) Number with lowest value
pow(x,y) X to the power of y
random() Random number between 0 and 1
round(x) Value of x rounded to its nearest integer
sin(x) Sine of x (x is in radians)
sqrt(x) Square root of x
tan(x) Tangent of an angle

Dates
Date() Create a new date object with the current date and time
Date(2017, 5, 21, 3, 23, 10, 0) Create a custom date object. The numbers represent year, month, day, hour, minutes, seconds, milliseconds. You can omit anything you want except for year and month.
Date(“2017-06-23”) Date declaration as a string
getDate() Get the day of the month as a number (1-31)
getDay() Get the weekday as a number (0-6)
getFullYear() Get the year as a four digit number (yyyy)
getHours() Get the hour (0-23)
getMilliseconds() Get the millisecond (0-999)
getMinutes() Get the minute (0-59)
getMonth() Get the month as a number (0-11)
getSeconds() Get the second (0-59)
getTime() Get the time (milliseconds since January 1, 1970)
getUTCDate() Day (date) of the month in the specified date according to universal time (also available for day, month, fullyear, hours, minutes etc.)
parse Parse a string representation of a date, and return the number of milliseconds since January 1, 1970
setDate() Set the day as a number (1-31)
setFullYear() Set the year (optionally month and day)
setHours() Set the hour (0-23)
setMilliseconds() Set the milliseconds (0-999)
setMinutes() Set the minutes (0-59)
setMonth() Set the month (0-11)
setSeconds() Set the seconds (0-59)
setTime() Set the time (milliseconds since January 1, 1970)
setUTCDate() Set the day of the month for a specified date according to universal time (also available for day, month, fullyear, hours, minutes etc.)

Node Properties
attributes Live collection of all attributes registered to an element
baseURI Absolute base URL of an HTML element
childNodes Collection of an element’s child nodes
firstChild First child node of an element
lastChild Last child node of an element
nextSibling Next node at the same node tree level
nodeName Name of a node
nodeType Type of a node
nodeValue Value of a node
ownerDocument Top-level document object for current node
parentNode Parent node of an element
previousSibling Node immediately preceding the current one
textContent Textual content of a node and its descendants

Node Methods
appendChild()Add a new child node to an element as the last child node
cloneNode() Clone HTML element
compareDocumentPosition() Compare the document position of two elements
getFeature() Return an object which implements the APIs of a specified feature
hasAttributes() Return true if an element has any attributes, else return false
hasChildNodes() Return true if an element has any child nodes, else return false
insertBefore() Insert a new child node before a specified, existing child node
isDefaultNamespace() Return true if a specified namespaceURI is the default, else return false
isEqualNode() Check if two elements are equal
isSameNode() Check if two elements are the same node
isSupported() Return true if a specified feature is supported on the element
lookupNamespaceURI() Return the namespaceURI associated with a given node
lookupPrefix() Return a DOMString containing the prefix for a given namespaceURI, if present
normalize() Join adjacent text nodes and remove empty text nodes in an element
removeChild() Remove a child node from an element
replaceChild() Replace a child node in an element

Element Methods
getAttribute() Return the specified attribute value of an element node
getAttributeNS() Return string value of the attribute with the specified namespace and name
getAttributeNode() Get the the specified attribute node
getAttributeNodeNS() Return the attribute node for the attribute with the given namespace and name
getElementsByTagName() Provide a collection of all child elements with the specified tag name
getElementsByTagNameNS() Return a live HTML collection of elements with a certain tag name belonging to the given namespace
hasAttribute() Return true if an element has any attributes, else return false
hasAttributeNS() Provide a true/false value indicating whether the current element in a given namespace has the specified attribute
removeAttribute() Remove a specified attribute from an element
removeAttributeNS() Remove the specified attribute from an element within a certain namespace
removeAttributeNode() Take away a specified attribute node and return the removed node
setAttribute() Set or change the specified attribute to a specified value
setAttributeNS() Add a new attribute or change the value of an attribute with the given namespace and name
setAttributeNode() Set or change the specified attribute node
setAttributeNodeNS() Add a new namespaced attribute node to an element

Browser Window Properties
closed Check whether a window has been closed or not and return true or false
defaultStatus Set or return the default text in the statusbar of a window
document Return the document object for the window
frames Return all

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