Javascript ES5 tutorial

 

Array every()

Array filter()

Array forEach()

Array indexOf()

Array lastIndexOf()

Array map()

Array reduce()

Array reduceRight()

Array some()

Array.isArray()

Date toISOString()

Date toJSON()

Date.now()

Function bind()

JSON.parse()

JSON.stringify()

Multiline strings

Object defineProperty()

Object methods

Property getters and setters

Reserved words as property names

String.trim()

String[number] access

Trailing commas

Use strict

ES5 Features topics	Explanation	ES5 Features Code Example
Array every()	Tests whether all elements in the array pass the test implemented by the provided function.	var allPositive = [1, 2, 3].every(function(number) { return number > 0; }); // true
Array filter()	Creates a new array with all elements that pass the test implemented by the provided function.	var filtered = [1, 2, 3, 4, 5].filter(function(number) { return number > 2; }); // [3, 4, 5]
Array forEach()	Executes a provided function once for each array element.	[1, 2, 3].forEach(function(number) { console.log(number); }); // logs 1, 2, 3
Array indexOf()	Returns the first index at which a given element can be found in the array, or -1 if it is not present.	var index = [1, 2, 3].indexOf(2); // 1
Array lastIndexOf()	Returns the last index at which a given element can be found in the array, or -1 if it is not present.	var lastIndex = [1, 2, 3, 2, 1].lastIndexOf(2); // 3
Array map()	Creates a new array with the results of calling a provided function on every element in this array.	var squared = [1, 2, 3].map(function(number) { return number * number; }); // [1, 4, 9]
Array reduce()	Apply a function against an accumulator and each value of the array (from left-to-right) to reduce it to a single value.	var sum = [1, 2, 3].reduce(function(total, number) { return total + number; }, 0); // 6
Array reduceRight()	Apply a function against an accumulator and each value of the array (from right-to-left) to reduce it to a single value.	var flattened = [[0, 1], [2, 3], [4, 5]].reduceRight(function(a, b) { return a.concat(b); }, []); // [4, 5, 2, 3, 0, 1]
Array some()	Tests whether at least one element in the array passes the test implemented by the provided function.	var hasNegative = [1, 2, 3, -1, 4].some(function(number) { return number < 0; }); // true
Array.isArray()	Determines whether the passed value is an Array.	var isArray = Array.isArray([1, 2, 3]); // true

ES5 Features topics	Explanation	ES5 Features Code Example
Date toISOString()	Converts a date to a string following the ISO 8601 Extended Format.	var dateStr = new Date().toISOString(); // 'YYYY-MM-DDTHH:mm:ss.sssZ'
Date toJSON()	Returns a string representation of the Date object in JSON format, which is actually the same as the Date's toISOString method.	var jsonDate = new Date().toJSON(); // 'YYYY-MM-DDTHH:mm:ss.sssZ'
Date.now()	Returns the number of milliseconds elapsed since January 1, 1970 00:00:00 UTC.	var timestamp = Date.now(); // e.g., 1367133733765
Function bind()	Creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called.	var obj = { x: 42 }; function func() { return this.x; } var boundFunc = func.bind(obj); console.log(boundFunc()); // 42
JSON.parse()	Parses a JSON string, constructing the JavaScript value or object described by the string.	var obj = JSON.parse('{"name":"John"}'); // {name: "John"}
JSON.stringify()	Converts a JavaScript object or value to a JSON string.	var jsonStr = JSON.stringify({name: "John"}); // '{"name":"John"}'
Multiline strings	Allows strings to be written across multiple lines without using string concatenation.	var multiStr = 'This is a \\ multiline string';
Object defineProperty()	Adds the named property described by a given descriptor to an object.	Object.defineProperty(obj, 'key', { value: 'static', writable: false }); obj.key; // 'static'
Object methods	Refers to the new methods added to the Object constructor: create, defineProperty, defineProperties, freeze, getOwnPropertyDescriptor, etc.	var descriptors = Object.getOwnPropertyDescriptor({name: 'John'}, 'name'); console.log(descriptors.value); // 'John'
Property getters and setters	Allows to define object properties that are accessed through getter/setter methods but look like regular properties to an external code.	var obj = { get x() { return 42; }, set x(v) { console.log('Setting x to', v); } };
Reserved words as property names	In ES5, reserved words like delete, void, return, etc., can be used as property names without error.	var obj = { 'delete': function() { /* ... */ }, 'void': 42 };
String.trim()	Removes whitespace from both ends of a string.	var trimmed = ' hello '.trim(); // 'hello'
String[number] access	Accesses the character in the string at the specified index using bracket notation.	var character = 'hello'[1]; // 'e'
Trailing commas	Allows commas to be placed after the last parameter in an array or object literal without causing an error.	var arr = [1, 2, 3,]; var obj = { foo: 'bar', };
Use strict	Directs the browser to enforce strict parsing and error handling of your JavaScript code.	'use strict'; var undeclaredVariable = 'This will throw an error if strict mode is on';