Let us first create a nested object −var details = {    "teacherDetails":    {       "teacherName": ["John", "David"]    },    "subjectDetails":    {       "subjectName": ["MongoDB", "Java"]    } }Let us now extract the keys. Following is the code −Examplevar details = {    "teacherDetails":    {       "teacherName": ["John", "David"]    },    "subjectDetails":    {       "subjectName": ["MongoDB", "Java"]    } } var objectName, nestedObject; var name = "Java"; for(var key in details){    for(var secondKey in details[key]){       if(details[key][secondKey].includes(name)){          objectName = ... Read More

To set sleep i.e. delay, use the concept of setTimeout(). It takes values in milliseconds i.e.1000 milliseconds = 1 second 2000 milliseconds = 2 seconds, etc.For our example, we will add two values with a delay of 5 seconds i.e. 5000 milliseconds. Following is the code −Examplevar firstValue=10; var secondValue=20; var result=firstValue+secondValue; setTimeout(function() { }, (5 * 1000)); console.log("The result="+result);The above setTimeout() will sleep for 5 seconds. To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo95.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo95.js The result=30Read More

To get largest numbers passed using reduce(), use the Math.max() function. Following is the code −const getBiggestNumberFromArraysPassed = allArrays => allArrays.reduce( (maxValue, maxCurrent) => maxValue.push(Math.max(...maxCurrent)),maxValue),[]); console.log(getBiggestNumberFromArraysPassed([[45,78,3,1],[50,34,90,89],[32,10,90,99]]));To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo94.jsOutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo94.js [ 78, 90, 99 ]

Let’s say the following are our two strings −var originalName = "JOHNDOE"; var removalName = "JOHN"We need to remove the second string from first. For this, use replace() along with reduce().Exampleconst removeCharactersFromAString= (removalName,originalName)=>removalName.split('').reduce((obj,v)=>obj.replace(v,''),originalName); var originalName = "JOHNDOE"; var removalName = "JOHN" console.log(removeCharactersFromAString(removalName,originalName));To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo93.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo93.js DOE

To un-nest array of objects, use the concept of map(). Let’s say the following are our array of objects −const studentDetails = [    {       "studentId": 101,       "studentName": "John",       "subjectDetails": {          "subjectName": "JavaScript"       }    },    {       "studentId": 102,       "studentName": "David",       "subjectDetails": {          "subjectName": "MongoDB"       }    } ];We need to un-nest the subjectName and display the result. Following is the code −Exampleconst studentDetails = [   ... Read More

To fetch the highest value, use the Math.max() from JavaScript. Since, we want the one with maximum value, use the Object.values.Exampleconst studentMarksDetails= {    marks1:78,    marks2:69,    marks3:79,    marks4:74 } const maximumMarks = Math.max(...Object.values(studentMarksDetails)); console.log("The highest marks="+maximumMarks); for (const key of Object.keys(studentMarksDetails)){    if (studentMarksDetails[key] == maximumMarks) {       console.log(`The Object='${key}'`);       break;    } }To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo91.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo91.js The highest marks=79 The Object='marks3'Read More

To remove extra spaces, you need to use trim() along with regular expressions. Following is our string with spaces before applying trim() −var sentence="My name is John Smith ";Now, we will remove the extra spaces as in the below code −Examplevar sentence="My name is John Smith "; console.log("The actual value="); console.log(sentence); var originalSentence = sentence.replace(/\s+/g, '').trim(); var afterRemovingTheSpace=originalSentence.trim(); console.log("After removing the spaces="); console.log(afterRemovingTheSpace);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo90.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo90.js The actual value= My name is John Smith After removing ... Read More

In order to modify the key values, you need to use regular expressions along with Object.fromEntries().Examplevar underscoreSpecifyFormat = str => str.replace(/(_)(.)/g, (_, __, v) => v.toUpperCase()), JsonObject = { first_Name_Field: 'John', last_Name_Field: 'Smith'}, output = Object.fromEntries(Object.entries(JsonObject).map(([key, value]) => [underscoreSpecifyFormat(key), value])); console.log("The JSON Object="); console.log(output);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo89.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo89.js The JSON Object= { firstNameField: 'John', lastNameField: 'Smith' }

To remove ‘0’. ‘undefined’ and empty values, you need to use the concept of splice(). Let’s say the following is our array −var allValues = [10, false, 100, 150 ,'', undefined, 450, null]Following is the complete code using for loop and splice() −Examplevar allValues = [10, false, 100, 150 ,'', undefined, 450, null] console.log("Actual Array="); console.log(allValues); for (var index = 0; index < allValues.length; index++) {    if (!allValues[index]) {       allValues.splice(index, 1);       index--;    } } console.log("After removing false, undefined, null or ''..etc="); console.log(allValues);To run the above program, you need to use the following ... Read More

To correctly iterate, use the document.getElementsByClassName(). The getElementsByClassName() is a methof od Document interface.Following is the cod wherein we are iterating through div classes −Example Live Demo Document My First JavaScript Program This is the second Program This is the third Program    var className = document.getElementsByClassName('demo');    for(var index=0;index < className.length;index++){       console.log(className[index].innerHTML);    } 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 −