Let’s say the following is our start value −var startValue=10;Let’s say the following is our end value −var endValue=20;Use the for loop to fetch numbers between the start and end value −Examplevar startValue=10; var endValue=20; var total=''; function printAllValues(startValue, endValue){    for(var start=startValue;start < endValue ;start++){       total=total+start+", ";    } } printAllValues(startValue, endValue) var allSequences = total.slice(0, -1); console.log(allSequences);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo87.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo87.js 10, 11, 12, 13, 14, 15, 16, 17, 18, 19Read More

At first, declare and initialize the total variable with 0 and then you need to iterate over all the array and extract all the values of array and add up with the updated total variable.Let’s say the following is our array with numbers −var listOfValues = [10, 3, 4, 90, 34, 56, 23, 100, 200];Examplevar listOfValues = [10, 3, 4, 90, 34, 56, 23, 100, 200]; var total = 0; for(let index = 0; index < listOfValues.length ; index++){    total=total+listOfValues[index]; } console.log("Total Values="+total);To run the above program, you need to use the following command −node fileName.js.Here, my file name ... Read More

To capitalize only the first letter, use the concept of regular expression along with toUpperCase(). Since the toUpperCase() capitalize the entire string, we need to use Regex to only capitalize the first letter after colon.Let’s say the following is our string −var objectValues='fullName: john Smith';Here’s the complete code to capitalize only the first letter after colon −Examplevar objectValues='fullName: john Smith'; function capitalizeFirstAfterTheColon(value){    return value.replace(/([:\?]\s+)(.)/g, function(data) {       return data.toUpperCase();    }); } console.log(capitalizeFirstAfterTheColon(objectValues));To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo85.js.OutputThis will produce the following output −PS ... Read More

To get objects with specific property, use the concept of reduce() on both arrays individually. You don’t need to concatenate. Let’s say the following are our objects with student name and student marksvar sectionAStudentDetails = [    {studentName: 'John', studentMarks: 78},    {studentName: 'David', studentMarks: 65},    {studentName: 'Bob', studentMarks: 98} ]; let sectionBStudentDetails = [    {studentName: 'John', studentMarks: 67},    {studentName: 'David', studentMarks: 89},    {studentName: 'Bob', studentMarks: 97} ];Following is the code to implement reduce() on both and fetch the object with higher value (marks) −Examplevar sectionAStudentDetails = [    {studentName: 'John', studentMarks: 78},    {studentName: 'David', ... Read More

Use the concept of map() along with ternary operator (?). Following are our array of objects −let firstCustomerDetails = [    {firstName: 'John', amount: 100},    {firstName: 'David', amount: 50},    {firstName: 'Bob', amount: 80} ];    let secondCustomerDetails = [    {firstName: 'John', amount: 400},    {firstName: 'David', amount: 70},    {firstName: 'Bob', amount: 40} ];Let’s say, we need to filter array of objects by amount property. The one with the greatest amount is considered.Examplelet firstCustomerDetails = [    {firstName: 'John', amount: 100},    {firstName: 'David', amount: 50},    {firstName: 'Bob', amount: 80} ]; let secondCustomerDetails = [   ... Read More

To create an array from JSON data, use the concept of map() from JavaScript. Let’s say the following is our data −const studentDetails =[    {       name : "John"    },    {       name : "David"    },    {       name : "Bob"    } ];Following is the code to create an array from the above data −Exampleconst studentDetails =[    {       name : "John"    },    {       name : "David"    },    {       name : "Bob"    } ]; const ListOfStudentName = studentDetails.map(({name:actualValue})=>actualValue); console.log(ListOfStudentName);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo82.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo82.js [ 'John', 'David', 'Bob']

Yes, JavaScript now supports the “null coalescing” operator, but you can also use the concept of logical OR (||). The syntax is as follows −var anyVariableName=null; var anyVariableName=yourVariableName || yourActualValue;Examplevar fullName=null; console.log("The full name is="+fullName); var actualName=fullName || "David Miller"; console.log("The full name is="+actualName);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo81.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo81.js The full name is=null The full name is=David Miller

The eval() is used to evaluate an argument in JavaScript. Following is the syntax −eval(str)Here, str can be an expression, variable or statement(s).Let’s say the following is our array −var studentMarks = [76,34,56,78,81,98,90,59,64];Now, fetch a specific value with eval(). Here, we are fetching the value at index 1 −Examplevar studentMarks = [76,34,56,78,81,98,90,59,64]; var stringValue = eval("studentMarks"); console.log(stringValue[1]);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo80.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo80.js 34

For this, use a “prototype”. JavaScript objects inherit properties and methods from a prototype. For accessing variables, we have also used the “this” in JavaScript.Examplefunction Customer(fullName){    this.fullName=fullName; } Customer.prototype.setFullName = function(newFullName){    this.fullName=newFullName; } var customer=new Customer("John Smith"); console.log("Using Simple Method = "+ customer.fullName); customer.setFullName("David Miller"); console.log("Using Prototype Method = "+customer.fullName);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo79.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo79.js Using Simple Method = John Smith Using Prototype Method = David MillerRead More

Let’s say the following is our Unordered List (ul) −    JavaScript Remove        MySQL Remove        MongoDB Remove        Java Remove Above, you can see the “Remove” button with every li element. On clicking this button, you can remove any li element.Following is the code to remove li elements on button click;Example Live Demo Document Remove the subjects The Subjects are as follows: JavaScript Remove MySQL Remove MongoDB Remove Java Remove    var allSubjectName = document.querySelectorAll(".subjectName");    for (var index = 0; index