**Javascript :** JavaScript is a lightweight, cross-platform, single-threaded, and interpreted compiled programming language. It is also known as the scripting language for webpages. It is well-known for the development of web pages, and many non-browser environments also use it. ## Some Basic Concepts - String ``` `Run each function to see the output, play and learn by doing // Length function getLength(str) { console.log("Original String:", str); console.log("Length:", str.length); } getLength("Hello World"); // indexOf function findIndexOf(str, target) { console.log("Original String:", str); console.log("Index:", str.indexOf(target)); } findIndexOf("Hello World", "World"); // lastIndexOf function findLastIndexOf(str, target) { console.log("Original String:", str); console.log("Index:", str.lastIndexOf(target)); } findLastIndexOf("Hello World World", "World"); // slice function getSlice(str, start, end) { console.log("Original String:", str); console.log("After slice:", str.slice(start, end)); } getSlice("HelloWorld", 2, 5); getSlice("HelloWorld", -5, -2); // substring function getSubstring(str, start, end) { console.log("Original String:", str); console.log("After substring:", str.substring(start, end)); } getSubstring("Hello World", 1, 5); getSubstring("Hello World", -5, -1); // replace function replaceString(str, target, replacement) { console.log("Original String:", str); console.log("After replace:", str.replace(target, replacement)); } replaceString("Hello World", "World", "JavaScript"); // split function splitString(str, separator) { console.log("Original String:", str); console.log("After split:", str.split(separator)); } splitString("Hello World", " "); // trim function trimString(str) { console.log("Original String:", str); console.log("After trim:", str.trim()); } trimString(" Hello World "); // toUpperCase function toUpper(str) { console.log("Original String:", str); console.log("After toUpperCase:", str.toUpperCase()); } toUpper("Hello World"); // toLowerCase function toLower(str) { console.log("Original String:", str); console.log("After toLowerCase:", str.toLowerCase()); } toLower("Hello World"); ` ``` - Number ``` function explainParseInt(value) { console.log("Original Value:", value); let result = parseInt(value); console.log("After parseInt:", result); } // Example Usage for parseInt explainParseInt("42"); explainParseInt("42px"); explainParseInt("3.14"); function explainParseFloat(value) { console.log("Original Value:", value); let result = parseFloat(value); console.log("After parseFloat:", result); } // Example Usage for parseFloat explainParseFloat("3.14"); explainParseFloat("42"); explainParseFloat("42px"); ``` - Array ``` function explainParseInt(value) { console.log("Original Value:", value); let result = parseInt(value); console.log("After parseInt:", result); } // Example Usage for parseInt explainParseInt("42"); explainParseInt("42px"); explainParseInt("3.14"); function explainParseFloat(value) { console.log("Original Value:", value); let result = parseFloat(value); console.log("After parseFloat:", result); } // Example Usage for parseFloat explainParseFloat("3.14"); explainParseFloat("42"); explainParseFloat("42px"); ``` - Class ``` class Animal { constructor(name, legCount) { this.name = name this.legCount = legCount } describe() { return `${this.name} has ${this.legCount} legs` } } let O1=new Animal("dog",4); let detail=O1.describe(); console.log(detail); ``` - Date ``` function dateMethods() { const currentDate = new Date(); console.log("Current Date:", currentDate); // Getting various components of the date console.log("Date:", currentDate.getDate()); console.log("Month:", currentDate.getMonth() + 1); // Months are zero-indexed, so adding 1 console.log("Year:", currentDate.getFullYear()); console.log("Hours:", currentDate.getHours()); console.log("Minutes:", currentDate.getMinutes()); console.log("Seconds:", currentDate.getSeconds()); // Setting components of the date currentDate.setFullYear(2022); console.log("After setFullYear:", currentDate); currentDate.setMonth(5); // Setting month to June (zero-indexed) console.log("After setMonth:", currentDate); // Getting and setting time in milliseconds since 1970 console.log("Time in milliseconds since 1970:", currentDate.getTime()); const newDate = new Date(2023, 8, 15); // Creating a new date console.log("New Date:", newDate); } // Example Usage for Date Methods dateMethods(); ``` - Json ``` function jsonMethods(jsonString) { console.log("Original JSON String:", jsonString); // Parsing JSON string to JavaScript object let parsedObject = JSON.parse(jsonString); console.log("After JSON.parse():", parsedObject); // Stringifying JavaScript object to JSON string let jsonStringified = JSON.stringify(parsedObject); console.log("After JSON.stringify():", jsonStringified); } // Example Usage for JSON Methods const sampleJSONString = '{"key": "value", "number": 42, "nested": {"nestedKey": "nestedValue"}}'; jsonMethods(sampleJSONString); ``` - **setInterval :** is a JavaScript function used to repeatedly execute a given function at fixed time intervals. It is commonly used for tasks that require periodic updates or actions on web pages, such as updating live data, creating animations, or implementing countdown timers. --- **Syntax** `setInterval(function, interval); ` ``` `// Example: Execute a function every 1 second const intervalId = setInterval(myFunction, 1000); function myFunction() { console.log("Executing function every 1 second"); } // To stop the interval after a certain period, you can use clearInterval: setTimeout(() => { clearInterval(intervalId); console.log("Interval stopped after 5 seconds."); }, 5000); ` ```

deepak1164

Basics Of Javascript

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