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awesome-cheatsheets/languages/javascript.js
2023-07-26 17:15:26 -04:00

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JavaScript

/* *******************************************************************************************
* GLOBAL OBJECTS > OBJECT
* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
* ******************************************************************************************* */
// Global object: properties
Object.length // length is a property of a function object, and indicates how many arguments the function expects, i.e. the number of formal parameters. This number does not include the rest parameter. Has a value of 1.
Object.prototype // Represents the Object prototype object and allows to add new properties and methods to all objects of type Object.
// Methods of the Object constructor
Object.assign(target, ...sources) // Copies the values of all enumerable own properties from one or more source objects to a target object. method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object
Object.create(MyObject) // Creates a new object with the specified prototype object and properties. The object which should be the prototype of the newly-created object.
Object.defineProperty(obj, prop, descriptor) // Adds the named property described by a given descriptor to an object.
Object.defineProperties(obj, props) // Adds the named properties described by the given descriptors to an object.
Object.entries(obj) // Returns an array containing all of the [key, value] pairs of a given object's own enumerable string properties.
Object.freeze(obj) // Freezes an object: other code can't delete or change any properties.
Object.getOwnPropertyDescriptor(obj, prop) // Returns a property descriptor for a named property on an object.
Object.getOwnPropertyDescriptors(obj) // Returns an object containing all own property descriptors for an object.
Object.getOwnPropertyNames(obj) // Returns an array containing the names of all of the given object's own enumerable and non-enumerable properties.
Object.getOwnPropertySymbols(obj) // Returns an array of all symbol properties found directly upon a given object.
Object.getPrototypeOf(obj) // Returns the prototype of the specified object.
Object.is(value1, value2); // Compares if two values are the same value. Equates all NaN values (which differs from both Abstract Equality Comparison and Strict Equality Comparison).
Object.isExtensible(obj) // Determines if extending of an object is allowed.
Object.isFrozen(obj) // Determines if an object was frozen.
Object.isSealed(obj) // Determines if an object is sealed.
Object.keys(obj) // Returns an array containing the names of all of the given object's own enumerable string properties.
Object.preventExtensions(obj) // Prevents any extensions of an object.
Object.seal(obj) // Prevents other code from deleting properties of an object.
Object.setPrototypeOf(obj, prototype) // Sets the prototype (i.e., the internal [[Prototype]] property).
Object.values(obj) // Returns an array containing the values that correspond to all of a given object's own enumerable string properties.
// Object instances and Object prototype object (Object.prototype.property or Object.prototype.method())
// Properties
obj.constructor // Specifies the function that creates an object's prototype.
obj.__proto__ // Points to the object which was used as prototype when the object was instantiated.
// Methods
obj.hasOwnProperty(prop) // Returns a boolean indicating whether an object contains the specified property as a direct property of that object and not inherited through the prototype chain.
prototypeObj.isPrototypeOf(object) // Returns a boolean indicating whether the object this method is called upon is in the prototype chain of the specified object.
obj.propertyIsEnumerable(prop) // Returns a boolean indicating if the internal ECMAScript [[Enumerable]] attribute is set.
obj.toLocaleString() // Calls toString().
obj.toString() // Returns a string representation of the object.
object.valueOf() // Returns the primitive value of the specified object.
/* *******************************************************************************************
* GLOBAL OBJECTS > ARRAY
* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
* ******************************************************************************************* */
// Global object: properties
Array.length // Reflects the number of elements in an array.
Array.prototype // Represents the prototype for the Array constructor and allows to add new properties and methods to all Array objects.
// Global object: methods
Array.from(arrayLike[, mapFn[, thisArg]]) // Creates a new Array instance from an array-like or iterable object.
Array.isArray(obj) // Returns true if a variable is an array, if not false.
Array.of(element0[, element1[, ...[, elementN]]]) // Creates a new Array instance with a variable number of arguments, regardless of number or type of the arguments.
// Instance: properties
arr.length // Reflects the number of elements in an array.
// Instance: mutator methods
arr.copyWithin(target, start, end) // Copies a sequence of array elements within the array.
arr.fill(value, start, end) // Fills all the elements of an array from a start index to an end index with a static value.
arr.pop() // Removes the last element from an array and returns that element.
arr.flat() // merges nested array into one single array
arr.push([element1[, ...[, elementN]]]) // Adds one or more elements to the end of an array and returns the new length of the array.
arr.reverse() // Reverses the order of the elements of an array in place — the first becomes the last, and the last becomes the first.
arr.shift() // Removes the first element from an array and returns that element.
arr.sort() // Sorts the elements of an array in place and returns the array.
array.splice(start, deleteCount, item1, item2, ...) // Adds and/or removes elements from an array.
arr.unshift([element1[, ...[, elementN]]]) // Adds one or more elements to the front of an array and returns the new length of the array.
// Instance: accessor methods
arr.at(index) // Returns the element at the specified index in the array.
arr.concat(value1[, value2[, ...[, valueN]]]) // Returns a new array comprised of this array joined with other array(s) and/or value(s).
arr.includes(searchElement, fromIndex) // Determines whether an array contains a certain element, returning true or false as appropriate.
arr.indexOf(searchElement[, fromIndex]) // Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found.
arr.join(separator) // Joins all elements of an array into a string.
arr.lastIndexOf(searchElement, fromIndex) // Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found.
arr.slice(begin, end) // Extracts a section of an array and returns a new array.
arr.toString() // Returns a string representing the array and its elements. Overrides the Object.prototype.toString() method.
arr.toLocaleString(locales, options) // Returns a localized string representing the array and its elements. Overrides the Object.prototype.toLocaleString() method.
// Instance: iteration methods
arr.entries() // Returns a new Array Iterator object that contains the key/value pairs for each index in the array.
arr.every(callback[, thisArg]) // Returns true if every element in this array satisfies the provided testing function.
arr.filter(callback[, thisArg]) // Creates a new array with all of the elements of this array for which the provided filtering function returns true.
arr.find(callback[, thisArg]) // Returns the found value in the array, if an element in the array satisfies the provided testing function or undefined if not found.
arr.findIndex(callback[, thisArg]) // Returns the found index in the array, if an element in the array satisfies the provided testing function or -1 if not found.
arr.forEach(callback[, thisArg]) // Calls a function for each element in the array.
arr.keys() // Returns a new Array Iterator that contains the keys for each index in the array.
arr.map(callback[, initialValue]) // Creates a new array with the results of calling a provided function on every element in this array.
arr.reduce(callback[, initialValue]) // Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value.
arr.reduceRight(callback[, initialValue]) // Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value.
arr.some(callback[, initialValue]) // Returns true if at least one element in this array satisfies the provided testing function.
arr.values() // Returns a new Array Iterator object that contains the values for each index in the array.
/* *******************************************************************************************
* GLOBAL OBJECTS > STRING
* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String
* ******************************************************************************************* */
// Global object: properties
String.length // Reflects the length of the string. Read-only.
String.prototype // Allows you to add properties and methods to the String object.
// Global object: methods
String.fromCharCode(num1[, ...[, numN]]) // Returns a string created from the specified sequence of UTF-16 code units.
String.fromCodePoint(num1[, ...[, numN]]) // Returns a string created from the specified sequence of code points.
String.raw(callSite, ...substitutions) // Returns a string created from a raw template string.
// Instance: properties
str.length // Reflects the length of the string. Read-only.
// Instance: methods
str.charAt(index) // Returns the specified character from a string.
str.charCodeAt(index) // Returns a number that is the UTF-16 code unit value at the given index.
str.codePointAt(index) // Returns a non-negative integer that is the Unicode code point value.
str.concat(string2, string3[,..., stringN]) // Combines the text of two or more strings and returns a new string.
str.endsWith(searchString[, length]) // Determines whether a string ends with the characters of a specified string.
str.includes(searchString[, position]) // Determines whether one string may be found within another string.
str.indexOf(searchValue[, fromIndex]) // Returns the index within the calling String object of the first occurrence of the specified value.
str.lastIndexOf(searchValue[, fromIndex]) // Returns the index within the calling String object of the last occurrence of the specified value.
str.localeCompare(compareString[, locales[, options]])// Returns a number indicating whether a reference string comes before, or after, or is the same as the given string in sort order.
str.match(regexp) // Retrieves the result of matching a string against a regular expression.
str.matchAll(regexp) // Returns an iterator of all results matching a string against a regular expression, including capturing groups.
str.normalize([form]) // Returns the Unicode Normalization Form of the string.
str.padEnd(targetLength [, padString]) // Pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length.
str.padStart(targetLength [, padString]) // Pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start of the current string.
str.repeat(count) // Constructs and returns a new string which contains the specified number of copies of the string on which it was called, concatenated together.
str.replace(regexp|substr, newSubstr|function) // Returns a new string with some or all matches of a pattern replaced by a replacement.
str.replaceAll(regexp|substr, newSubstr|function) // Returns a new string with all matches of a pattern replaced by a replacement.
str.search(regexp) // Executes a search for a match between a regular expression and this String object.
str.slice(beginIndex[, endIndex]) // Extracts a section of a string and returns it as a new string.
str.split([separator[, limit]]) // Divides a String into an ordered list of substrings, puts these substrings into an array, and returns the array.
str.startsWith(searchString[, position]) // Determines whether a string begins with the characters of a specified string.
str.substring(indexStart[, indexEnd]) // Returns the part of the string between the start and end index.
str.toLocaleLowerCase([locale, localeN]) // The characters within a string are converted to lower case while respecting the current locale.
str.toLocaleUpperCase([locale, localeN]) // The characters within a string are converted to upper case while respecting the current locale.
str.toLowerCase() // Returns the calling string value converted to lowercase.
str.toString() // Returns a string representing the specified object. Overrides the Object.prototype.toString() method.
str.toUpperCase() // Returns the calling string value converted to uppercase.
str.trim() // Trims whitespace from the beginning and end of the string.
str.trimStart() // Trims whitespace from the beginning of the string.
str.trimEnd() // Trims whitespace from the end of the string.
/* *******************************************************************************************
* GLOBAL OBJECTS > NUMBER
* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number
* ******************************************************************************************* */
// Global object: properties
Number.EPSILON // Represents the difference between 1 and the smallest floating-point number greater than 1.
Number.MAX_SAFE_INTEGER // Represents the maximum safe integer in JavaScript (2^53 - 1).
Number.MAX_VALUE // Represents the maximum positive finite value of JavaScript.
Number.MIN_SAFE_INTEGER // Represents the minimum safe integer in JavaScript (-(2^53 - 1)).
Number.MIN_VALUE // Represents the smallest positive finite value of JavaScript.
Number.NaN // Special "Not a Number" value.
Number.NEGATIVE_INFINITY // Represents negative infinity.
Number.POSITIVE_INFINITY // Represents positive infinity.
Number.prototype // Allows you to add properties and methods to a Number object.
// Global object: methods
Number.isFinite(value) // Determines whether the passed value is a finite number.
Number.isInteger(value) // Determines whether the passed value is an integer.
Number.isNaN(value) // Determines whether the passed value is NaN.
Number.isSafeInteger(value) // Determines whether the provided value is a number that is a safe integer.
Number.parseFloat(string) // Parses a string argument and returns a floating point number.
Number.parseInt(string[, radix]) // Parses a string argument and returns an integer of the specified radix or base.
// Instance: methods
numObj.toExponential([fractionDigits]) // Returns a string representing the number in exponential notation.
numObj.toFixed([digits]) // Returns a string representing the number in fixed-point notation.
numObj.toLocaleString([locales[, options]]) // Returns a string with a language sensitive representation of this number. Overrides the Object.prototype.toLocaleString() method.
numObj.toPrecision([precision]) // Returns a string representing the number to a specified precision in fixed-point or exponential notation.
numObj.toString([radix]) // Returns a string representing the specified object. Overrides the Object.prototype.toString() method.
numObj.valueOf() // Returns the primitive value of a Number object.