Javascript Articles - Page 408 of 671

Following is the code to convert a node list to an array in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .sample {       display: inline-block;       font-size: 20px;       font-weight: 500;       color: white;       background-color: blue;       padding:10px;       width: 100px;       height: 100px;    } Convert a node list to an array 1 2 3 4 CLICK HERE Click on the above button to change colors of all the above div    let sampEle = document.querySelectorAll('.sample');    let BtnEle = document.querySelector('.Btn');    BtnEle.addEventListener('click',()=>{       Array.from(sampEle).forEach(item=>{          item.style.backgroundColor = 'red';       })    }) OutputOn clicking the ‘CLICK HERE’ button −

Following is the code to check if a property is in an object in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result {       font-size: 20px;       font-weight: 500;       color: blueviolet;    } Checking a property in an object CLICK HERE Click on the above button to check if firstName property is present in obj object    let resEle = document.querySelector(".result");    let obj = { firstName: "Rohan", lastName: "Sharma", ... Read More

Following is the code to implement pseudo mandatory parameters in functions in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result {       font-size: 20px;       font-weight: 500;       color: blueviolet;    } Optional function parameters CLICK HERE Click on the above button to call the add() and multiply() function    let resEle = document.querySelector(".result");    function add(a = 0, b = 0) {       return a + b;    }    function multiply(a, b) {       a = a || 0;       b = b || 0;       return a + b;    }    document.querySelector(".Btn").addEventListener("click", () => {       resEle.innerHTML = "Sum of the numbers = " + add() + "";       resEle.innerHTML +=       "Multiplication of the numbers = " + multiply() + "";    }); OutputOn clicking the ‘CLICK HERE’ button −

The consice arrow is more stream lined form of fat arrow functions for one-line functions. If the function body only has one line of code, then there isn’t any need of curly braces {} for function body as conscie arrow functions have implicit return. Also, if there is only one parameter then that can be written without the parenthesis () but if there is no parameter then the parenthesis is necessary.SyntaxFat arrow function −let add = (a, b) =>{return a+b;}Consice arrow function:let add = (a, b)=>a+b;If one parameter only −let add = a=>a+22;Following is the code for fat vs concise ... Read More

The conscise arrow function syntax is as follows −(param1, param2) =>param1+param2It doesn’t have the function keyword and the function body. There is only => between the parameters and function body and if there is single parameter than it can also be written like this −param1=>param1*2It has implicit return if there aren’t curly braces {} after the =>.Following is the code to implement concise arrow functions in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result {       font-size: 20px;     ... Read More

The fat arrow function syntax looks like the following −(param1, param2, ..)=>{ }It doesn’t have the function keyword and only have the => between the parameters and the function body.Following is the code implementing fat arrow functions in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result{       font-size: 20px;       font-weight: 500;       color: blueviolet;    } Fat arrow functions CLICK HERE Click on the above button to call the add() fat ... Read More

Following is the code for passing parameters to callback functions in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result{       font-size: 20px;       font-weight: 500;       color: blueviolet;    } Passing parameters to callback functions CLICK HERE Click on the above button to pass parameter to callback function add2 and call it    let resEle = document.querySelector(".result");    function add2(a) {       return a + 2;    }    function multiply9(fn, num) {       return fn(num) * 9;    }    document.querySelector(".Btn").addEventListener("click", () => {       resEle.innerHTML = "The number returned = " + multiply9(add2, 8);    }); OutputOn clicking the ‘CLICK HERE’ button −

To empty an array in JavaScript, there are four ways −Setting to new Array − In this we set our array variable to a new empty array.Using length property − In this we set the length property of our array to 0.Using pop − In this we continuously pop the array elements till the length reaches to 0.Using splice − In this we put the start index as 0 and the no of elements to removed as array.length-1.Following is the code to display no. of ways to empty an array in JavaScript −Example Live Demo Document ... Read More

Following is the code to implement asynchronous loop in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result {       font-size: 20px;       font-weight: 500;       color: blueviolet;    } Asynchronous loop in JavaScript CLICK HERE Click on the above button to start our asynchronous loop    let resEle = document.querySelector(".result");    async function waitTime(time) {       return new Promise((resolve) => {          setTimeout(resolve, time);       });    }    async function someFunction() {       for (let i = 0; i < 10; i++) {          await waitTime(2000);          resEle.innerHTML += "i = " + i + "";       }    }    document.querySelector(".Btn").addEventListener("click", () => {       someFunction();    }); OutputOn clicking the ‘CLICK HERE’ button the loop will print 1 to 10 −

The best way to add an event to any element is to use the addEventListener() method.Following is the code to add an event in JavaScript −Example Live Demo Document    body {       font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;    }    .result{       font-size: 20px;       font-weight: 500;       color: rebeccapurple;    } Adding event in JavaScript CLICK HERE Click on the above button to increment the font size of above text    let resEle = document.querySelector(".result");    document.querySelector(".Btn").addEventListener("click", () => {       resEle.style.fontSize = "34px";    }); OutputThe above code will produce the following output −On clicking the ‘CLICK HERE’ button −