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Object Oriented Programming Articles
Page 384 of 588
How to convert an object into an array in JavaScript?
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' ]
Read MoreHow can I cut a string after X characters in JavaScript?
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 MoreFinding content of arrays on the basis of specific property in JavaScript?
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 MoreHow can we separate the special characters in JavaScript?
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 MoreCheck if string begins with punctuation in JavaScript
Let’s say we have the following strings. One of them is beginning with a question mark i.e. punctuation −var sentence1 = 'My Name is John Smith.' var sentence2 = '? My Name is John Smith.'We need to check whether any of the above two sentences begin with punctuation. To check if string begins with punctuation, the code is as follows −Examplevar punctuationDetailsRegularExpression=/^[., :!?]/ var sentence1 = 'My Name is John Smith.' var output1 = !!sentence1.match(punctuationDetailsRegularExpression) if(output1==true) console.log("This ("+sentence1+") starts with a punctuation"); else console.log("This ("+sentence1+") does not starts with a punctuation"); var sentence2 = '? My Name is ...
Read MoreRemove the whitespaces from a string using replace() in JavaScript?
Let’s say the following is our string with whitespace −var fullName=" John Smith ";Use replace() and set Regex in it to remove whitespaces.Examplefunction removeSpacesAtTheBeginningAndTheEnd(name) { return name.toString().replace(/^\s+|\s+$/g,''); } var fullName=" John Smith "; var valueAfterRemovingSpace=removeSpacesAtTheBeginningAndTheEnd(fullName) console.log(valueAfterRemovingSpace);To run the above program, you need to use the following command −node fileName.js.Here my file name is demo208.js.OutputThis will produce the following output −PS C:\Users\Amit\javascript-code> node demo208.js John Smith
Read MoreBest way to find two numbers in an array whose sum is a specific number with JavaScript?
Let’s say the following is our array −var numbers = [10, 3, 40, 50, 20, 30, 100]We need to search two numbers from the above array elements, whose sum is 80.For this, use simple for loop with if condition.Examplefunction specificPairsOfSumOfTwoNumbers(numbers, totalValue) { var storeTwoNumbersObject = {} for(var currentNumber of numbers) { if(storeTwoNumbersObject[currentNumber]) { return { firstNumber: totalValue-currentNumber, secondNumber:currentNumber} } ...
Read MoreJavaScript How to get all 'name' values in a JSON array?
Let’s say the following is our JSON array −var details = [ { "customerDetails": [ { "customerName": "John Smith", "customerCountryName": "US" } ] }, { "customerDetails": [ { "customerName": "David Miller", "customerCountryName": "AUS" } ] }, { ...
Read MoreJavaScript Remove all '+' from array wherein every element is preceded by a + sign
Let’s say the following is our array with elements preceded by a + sign −var studentNames = [ '+John Smith', '+David Miller', '+Carol Taylor', '+John Doe', '+Adam Smith' ];To remove the + sign, the code is as follows −ExamplestudentNames = [ '+John Smith', '+David Miller', '+Carol Taylor', '+John Doe', '+Adam Smith' ]; console.log("The actual array="); console.log(studentNames); studentNames = studentNames.map(function (value) { return value.replace('+', ''); }); console.log("After removing the + symbol, The result is="); console.log(studentNames);To run the above program, you need to use the following command −node fileName.js.Here my file ...
Read MoreAccess previously iterated element within array.map in JavaScript?
Let’s say the following is our array −var details = [ {subjectId:110, subjectName: 'Java' }, {subjectId:111, subjectName: 'Javascript' }, {subjectId:112, subjectName: 'MySQL' }, {subjectId:113, subjectName: 'MongoDB' } ];Now, use the concept of map(). The code is as follows −Examplevar details = [ {subjectId:110, subjectName: 'Java' }, {subjectId:111, subjectName: 'JavaScript' }, {subjectId:112, subjectName: 'MySQL' }, {subjectId:113, subjectName: 'MongoDB' } ]; var output = details.map((detailsObject, index) => { var tempObject = {}; tempObject.subjectId= detailsObject.subjectId; tempObject.subjectName = detailsObject.subjectName; const getThePreviousObject = index != 0 ? details[index-1] : null; tempObject.previousSubjectName = ...
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