JavaScript ES5 (JS 2009)

JavaScript 2009 (ES5) refers to the fifth edition of the ECMAScript language specification, standardized in 2009. It introduced several features, like strict mode, new methods, JSON support, and improved syntax for better programming practices and compatibility across browsers.

ECMAScript 5 (ES5) introduced several significant features to JavaScript, enhancing the language's capabilities.

Here is the explanation of above-mentioned topic

Method 1: use strict

The use strict enforces strict mode in JavaScript, catching errors and promoting better coding practices. It's used at the beginning of scripts or functions.

Syntax:

// Whole-script strict mode syntax
'use strict';
 let v = "strict mode script!";

Example: In this example we are using the above-explained method.

Output:

ReferenceError: result is not defined

Method 2: String.trim() Method

JavaScript String trim() method is used to remove the white spaces from both ends of the given string.

Syntax:

str.trim()

Example: In this example we are using the above-explained method.

GeeksforGeeks

Method 3: Multiline Strings

In ES5, multiline strings can be created using backslashes at the end of each line to continue, combined with + for concatenation, to form a single string across lines.

Syntax:

line one\n\
line two\n\

Example: In this example we are using backslashes and + to write Multiline strings.

GeeksforGeeks A computer science Portal.
GeeksforGeeks

Method 4: Array Methods (Array.isArray(), Array.map(), Array.filter(), and Array.reduce() Methods)

• The Array.isArray() method checks if a value is an array or not and returns true or false.
• The Array.map() method transforms each element in an array using a provided function, returning a new array.
• Array.filter() method creates a new array with elements that satisfy a condition set by a function.
• The Array.reduce() method reduces array to a single value by executing a function with accumulator.

Syntax:

Array.isArray(obj) 
map((element) => { /* … */ }) 
array.filter(callback(element, index, arr), thisValue) 
array.reduce( function(total, currentValue, currentIndex, arr), initialValue )

Example: In this example we are using the above-explained methods.

Is 'numbers' an array? true
doubling each elemen of our array : [ 2, 4, 6, 8, 10 ]
Even numbers from the array: [ 2, 4 ]
Sum of all elements in the array: 15

Method 5: JSON.parse() Method

The JSON.parse() method is a JavaScript method that converts a JSON string into a JavaScript object.

Syntax:

JSON.parse( string, function )

Example: Here is the basic example of JSON.parse() method.

Aman
21
Noida

Method 6: JSON.stringify() Method

JSON.stringify() is a JavaScript method that converts a JavaScript object into a JSON string for data serialization and storage.

Syntax:

JSON.stringify(value, replacer, space);

Example: In this example we are using JSON.stringify().

value of result = {"Company":"GeeksforGeeks","Estd":2009,"location":"Noida"}

Date Methods (Date.now(),Date toISOString() and Date toJSON() Methods)

• Date.naw() method used to return the number of milliseconds elapsed since January 1, 1970, 00:00:00 UTC.
• Date toISOString() converts a date to an ISO 8601 format string (e.g., "YYYY-MM-DDTHH:mm:ss.sssZ").
• Date toJSON() method converts the given date object’s contents into a string.

Syntax:

let A = Date.now(); // Date.now()
dateObj.toISOString() // Date toISOString()
dateObj.toJSON() // Date toJSON()

Example: In this example we are using the abobe-explained methods.

Timestamp: 1698213643835
ISO String: 2023-10-25T06:00:43.835Z
JSON Date: 2023-10-25T06:00:43.835Z

Method 7: Property Getters and Setters

In ECMAScript 5 (ES5), property getters and setters enable defining custom behavior when reading (get) or modifying (set) object properties, enhancing encapsulation and control over property access.

Example: In this example we are using the above-explained approach.

John Doe
Jane
Smith

Method 8: New Object Property Methods

ECMAScript 5 introduced new object methods

• Object.defineProperty(),
• Object.defineProperties()
• Object.getOwnPropertyDescriptor()
• Object.keys()
• Object.getOwnPropertyNames()
• Object.preventExtensions()
• Object.isExtensible()
• Object.seal()
• Object.isSealed()
• Object.freeze()
• Object.isFrozen()

It enhance the object property control, definition, and manipulation.

Syntax:

Object.defineProperty(obj, prop, descriptor) // Object.defineProperty()
Object.defineProperties(obj, props) // Object.defineProperties()
Object.getOwnPropertyDescriptor( obj, prop ) // Object.getOwnPropertyDescriptor()
Object.keys(obj); // Object keys() Method

Example: In this example we are some mentioned method.