Hoisting allows us to call functions and variables (declared with var) before they are being defined by moving them to the top of their scope before the execution of code begins.Following is the code showing hoisting for variables and functions in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result, .sample {       font-size: 20px;       font-weight: 500;    } Hoisting in JavaScript Calling functions and variables before they are defined CLICK HERE ... Read More

Note − To run this example you will need to run a localhost server.Following is the code for importing and exporting a module/library in JavaScript −ExampleINDEX.html Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result {       font-size: 18px;       font-weight: 500;    } JavaScript Importing and Exporting Modules IMPORT Click on the above button to import module script.jsimport test from './sample.js'; document.querySelector('.Btn').addEventListener('click', ()=>{    test(); })sample.jslet resultEle = document.querySelector(".result"); export default ... Read More

The dotAll flag returns true or false depending upon if the s flag has been set in the regular expression or not.Following is the code to implement dotAll flag for regular expressions in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result {       font-size: 20px;       font-weight: 500;    } dotAll flag for regular expressions CLICK HERE Click on the above button to know if s flag has been set in regex or ... Read More

The promise.finally() calls the callback function whether a promise has been fulfilled or rejected. This helps us to do something once the promise has been rejected or resolved.Following is the code for Promise.finally() in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result {       font-size: 20px;       font-weight: 500;    } Promise.finally in JavaScript CLICK HERE Click on the above button to know when the promise finishes    let btnEle = ... Read More

With JavaScript, you can group s part of regular expression. This can be done by encapsulating characters in parentheses.Following is an example −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .sample, .result {       font-size: 20px;       font-weight: 500;    } Named capture groups Regular Expressions The year in which i passed school was 2012. CLICK HERE Click on the above button to extract the year using named groups    let sampleEle = ... Read More

Lookbehind allows matching a pattern only if there’re something before.Following is an example −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .sample, .result {       font-size: 20px;       font-weight: 500;    } Look behind Assertions Regular Expressions The price for 4 tables are $50 , $99 , $121 and $150. CLICK HERE Click on the above button to extract the table price using lookbehind    let sampleEle = document.querySelector(".sample").innerHTML;    let btnEle = document.querySelector(".btn");    let resEle = document.querySelector(".result");    const priceRegex=/(? {       resEle.innerHTML = "Table price are = "+sampleEle.match(priceRegex);    }); OutputThe above code will produce the following output −On clicking the ‘CLICK HERE’ button −

The Unicode property escapes regular expressions, allow us to match characters based on their Unicode properties by using the flag u.ExampleFollowing is an example − Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .sample, .result {       font-size: 20px;       font-weight: 500; } Unicode Property Escapes JavaScript Regular Expressions Hello 😆😀 World 🙂😊 CLICK HERE Click on the above button to extract the emojis using regex    let sampleEle = document.querySelector(".sample").innerHTML;    let btnEle ... Read More

The rest operator (…) allows us to call a function with any number of arguments and then access those excess arguments as an array. The rest operator also allows us in destructuring array or objects.The spread operator (…) allows us to expand an iterable like array into its individual elements.ExampleFollowing is the code showing the rest and spread operator in JavaScript − Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .sample, .result {       font-size: 20px;       font-weight: 500;    } ... Read More

For this, use preventDefault() in JavaScript. Following is the JavaScript code −Example Live Demo Document Press Me to see logs Press Me to see logs in console Nothing will happen    $(function(){       $("a:not([href='#'])").click(function(event){          event.preventDefault();          console.log("You have pressed me!!!!!");       });    }); To run the above program, save the file name anyName.html(index.html) and right click on the file. Select the option Open with live server in VS code editor.OutputIf you click the two links, Press Me ... Read More

For this, you need to use keyDown as well as preventDefault(). Following is the JavaScript code −Example Live Demo Document    const pressEnter = (event) => {       if (event.key === "Enter") {          event.preventDefault();       }    };    document.getElementById("disableDefaultTime").addEventListener("keydown",    pressEnter); To run the above program , just save the file name anyName.html(index.html) and right click on the file and select the option open with live server in VSCode editor.OutputFollowing is the output. When you press Enter key nothing will be displayed.You need to use keyDown to get time as in the below screenshot −