The easiest way to detect keypresses in JavaScript, use the onKeyPress event handler −document.onkeypressThe key press is matched with the keyCode property, which returns the Unicode character code of the key that triggered the onkeypress event.Example Live Demo Document    document.onkeypress = function (eventKeyName) {       eventKeyName = eventKeyName || window.event;       if(eventKeyName.keyCode==13){          console.log('You have pressed enter key');       } else {          alert(String.fromCharCode(eventKeyName.keyCode))    } }; To run the above program, save the file name ... Read More

To find out which characters key is pressed, use the window.event along with keyCode. Following is the code −Example Live Demo Document    function keyPressName(myEventKeyName){       var pressedKey;       if(window.event){          pressedKey = myEventKeyName.keyCode;       } else if(myEventKeyName.which)       {          pressedKey = myEventKeyName.which;    }    alert(String.fromCharCode(pressedKey)); } 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” ... Read More

To avoid unexpected string concatenation while concatenating strings, multiple strings, and numbers, use backticks.We have the following −const concatValue = 'John, David, Mike'; var friendNames= `${concatValue}`;The above value is concatenated with a string and number −var studentNameWithFriends=` ${concatValue}| 'Carol' | 24 ` ;Following is the complete JavaScript code for concatenation −Exampleconst concatValue = 'John, David, Mike'; var friendNames= `${concatValue}`; var studentNameWithFriends=` ${concatValue}| 'Carol' | 24 ` ; console.log(friendNames); console.log(studentNameWithFriends);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo37.jsOutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo37.js John, David, Mike John, ... Read More

To display only the visible text, use the concept of − visible selector in jQuery. It selects the element currently visible. Following is the code −Example Live Demo Document Test Class Demo class    $('#myDiv').children(":visible").text() 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.This will produce the following output displaying the visible text −

To parse JSON, use parseJSON() and for displaying a specific pair, use the $.each() function.Let’s say the following is our JSON, which is parsed −const APIData = '[{"Name":"John", "Age":21}, {"Name":"David", "Age":24}, {"Name":"Bob", "Age" :20}]'; const getObject = jQuery.parseJSON(APIData);Now, let’s see the complete code and fetch the “Name” pairs −Example Live Demo Document    const APIData =    '[{"Name":"John", "Age":21}, {"Name":"David", "Age":24}, {"Name":"Bob", "Age":20}]';    const getObject = jQuery.parseJSON(APIData);    $.each(getObject, function (k, obj) {       console.log(obj['Name']);    }); To run the above program, save the file name ... Read More

To find all subsets of a set, use reduce() along with map() in JavaScript. Let’s say, we are passing the set [8,9] and finding the subsets.Exampleconst findAllSubsetsoOfGivenSet = originalArrayValue => originalArrayValue.reduce(    (givenSet, setValue) => givenSet.concat(       givenSet.map(givenSet => [setValue,...givenSet])    ), [[]] ); console.log(findAllSubsetsoOfGivenSet([8,9]));To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo36.js.OutputThis will produce the following output.PS C:\Users\Amit\JavaScript-code> node demo36.js [ [], [ 8 ], [ 9 ], [ 9, 8 ] ]

To convert an object into an array, use push() in JavaScript. Following is the code −ExamplestudentDetails=   [       { studentName:"Chris",studentMarks:34},       { studentName:"David",studentMarks:89} ] var convertIntoArray = []; for (var i = 0; i < studentDetails.length; i++) {    convertIntoArray.push(studentDetails[i].studentName); } console.log(convertIntoArray);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo35.js.OutputThis will produce the following output.PS C:\Users\Amit\JavaScript-code> node demo35.js [ 'Chris', 'David' ]

To cut a string after X characters, use substr() function from JavaScript. Following is the JavaScript code wherein we are cutting the string after 9th character −Examplevar myName="JohnSmithMITUS"; console.log("The String="+myName) var afterXCharacter = myName.substr(0, 9) + "\u0026"; console.log("After cutting the characters the string="+afterXCharacter);Above, the unicode “\u0026” will replace all the characters with &(“\u0026”).To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo34.js.OutputThis will produce the following output.PS C:\Users\Amit\JavaScript-code> node demo34.js The String=JohnSmithMITUS After cutting the characters the string=JohnSmith&Read More

For this, you can use find() along with a map(). Let’s say we have student records with name, rollno and subject.Examplevar firstObject= [    { "FirstName": "David", "RollNo": "105", "Subject": "MongoDB" },    { "FirstName": "Mike", "RollNo": "110", "Subject": "JavaScript"} ]; var secondObject= [    { "FirstName": "Bob", "RollNo": "101", "Subject": "Java" },    { "FirstName": "John", "RollNo": "110", "Subject": "MySQL" } ]; var output = firstObject.map(first=>(secondObject.find(second=>second.RollNo==first.R ollNo) || first)); console.log(output);To run the above program, you need to use the following command −node fileName.jsHere, my file name is demo33.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo33.js [   ... Read More

To separate the special character, use the concept of match() with Regular Expression. The syntax is as follows −yourStringName.flatMap(anyVariableName => yourVariableName.match(/\w+|\W+/g));Let’s say, the following is our array with special characters in between values −var allNames = ['John-Smith', 'David', 'Carol%Taylor'];Let’s now see how to separate text with special characters. Following is the code −Examplevar allNames = ['John-Smith', 'David', 'Carol%Taylor']; var output = allNames.flatMap(obj => obj.match(/\w+|\W+/g)); console.log(output);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo32.js.OutputThis will produce the following output −PS C:\Users\Amit\JavaScript-code> node demo32.js [    'John', '-',    'Smith', 'David',   ... Read More