For this, use the concept of reduce(). Following is the code −Exampleconst subjectDetails = [    {       subjectId: '101',       subjectName: 'JavaScript'    },    {       subjectId: '102',       subjectName: 'Java'    },    {       subjectId: '103',       subjectName: 'JavaScript'    } ]; console.log([...subjectDetails.reduce((obj1, obj2) => {    if (obj1.has(obj2.subjectName)){       obj1.get(obj2.subjectName).frequency++;    } else {       obj1.set(obj2.subjectName, { subjectName: obj2.subjectName,       frequency: 1 });    }    return obj1; }, new Map()).values()]);To run the above program, you need ... Read More

To create, use add() method, whereas to delete created and appended element, you can use remove(). Following is the code −Example Live Demo Document Add A New Name AddName    var givenName = document.querySelector('#name')    var btnClass = document.querySelector('#addNameButton')    var listOfName = document.querySelector('#listOfName')    btnClass.addEventListener('click', () => {       var actualName = givenName.value       if (actualName.length != 0) {          var createAnHTMLList = `${actualName}Remove Name`          listOfName.innerHTML += ... Read More

Let’s get the current date first −var currentDate = new Date(); console.log("The current date is as follows="+currentDate);Now, let us remove seconds/ milliseconds by setting them to 0 using setSeconds() −currentDate.setSeconds(0, 0);Convert to ISO String using toISOString() −currentDate.toISOString()Let us now see the complete code with output −Examplevar currentDate = new Date(); console.log("The current date is as follows="+currentDate); currentDate.setSeconds(0, 0); console.log("After removing seconds from date, the new date is as follows="); console.log(currentDate.toISOString());To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo143.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo143.js The current date ... Read More

To toggle hide class only on selected div, you need to set event on click button. Let’s say you need to hide a specific div on the click of + sign.To get font + or - icon, you need to link font-awesome −Following is the code to toggle hide class on clicking + sign −Example Live Demo Document .hideDiv { display: none; } Customer 1 John US Customer 2 David AUS $(".fa-plus").on("click", function(){ $(this).parent().siblings('.secondDetails').toggleClass("hideDiv"); }); To run ... Read More

Let’s say the following are our arrays −var firstNamesArray=["John", "David", "Bob", "Sam", "Carol"]; var secondNamesArray=["Mike", "Carol", "Adam", "David"];The easiest way to perform array intersection is by using filter() along with includes(). Following is the code −Examplevar firstNamesArray=["John", "David", "Bob", "Sam", "Carol"]; var secondNamesArray=["Mike", "Carol", "Adam", "David"]; var intersectionOfArray=[]; intersectionOfArray=firstNamesArray.filter(v => secondNamesArray.includes(v)); console.log("Intersection of two array="); console.log(intersectionOfArray);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo141.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo141.js Intersection of two array= [ 'David', 'Carol' ]Read More

For this, use hasOwnProperty(). Following is the code −Examplevar markDetails1 ={    'marks1': 78,    'marks2': 65 }; var markDetails2 ={    'marks2': 89,    'marks3': 90 } function updateJavaScriptObject(details1, details2) {    const outputObject = {};    Object.keys(details1)    .forEach(obj => outputObject[obj] =    (details2.hasOwnProperty(obj) ? details2[obj] : details1[obj]));    return outputObject; } console.log(updateJavaScriptObject(markDetails1, markDetails2));To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo140.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo140.js { marks1: 78, marks2: 89 }

For this, you can use match() along with regular expression. Following is the code −Examplevar originalString="JJJJOHHHHNNNSSSMMMIIITTTTHHH"; var regularExpression=/(.)\1*/g; console.log("The original string="+originalString); var splitting=originalString.match(regularExpression); console.log("After splitting the original string="); console.log(splitting);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo139.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo139.js The original string=JJJJOHHHHNNNSSSMMMIIITTTTHHH After splitting the original string=[    'JJJJ', 'O',    'HHHH', 'NNN',    'SSS', 'MMM',    'III', 'TTTT',    'HHH' ]

Let’s say following is our array −var numbers=[10,50,80,60,89];To find the second largest element, the code is as follows −Examplevar numbers=[10,50,80,60,89]; var firstLargerNumber = Number.MIN_SAFE_INTEGER; var secondlargerNumber = firstLargerNumber; for(var tempNumber of numbers){    if(tempNumber > firstLargerNumber){       secondlargerNumber = firstLargerNumber;       firstLargerNumber = tempNumber;    }    else if(tempNumber > secondlargerNumber){       secondlargerNumber = tempNumber;    } } console.log("The second largest number="+secondlargerNumber);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo138.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo138.js The second largest number=80

Let’s say the following is our button −SubmitOn the basis of button id, on form submission, generate an alert −$("#submitForm").click(function() {    alert("The Form has been Submitted."); });Example Live Demo Document CollegeId= CollegeName=  Submit    $("#submitForm").click(function() {       alert("The Form has been Submitted.");    }); 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.OutputThis will produce the following output −After clicking the button, you can see the following output −

To get the yesterday date, first of all get the current date and subtract 1 from the current and use the function setDate(). The syntax is as follows −yourCurrentDateVariableName.setDate(yourCurrentDateVariableName.getDate() - 1);At first, get the current date −var currentDate = new Date();Now, get yesterday’s date with the following code −Examplevar currentDate = new Date(); console.log("The current date="+currentDate); var yesterdayDate = currentDate.setDate(currentDate.getDate()- 1); console.log("The yesterday date ="+new Date(yesterdayDate));To run the above program, you need to use the following command −node fileName.js.OutputHere, my file name is demo137.js. This will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo137.js The current date=Fri Jul 31 2020 ... Read More