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Articles on Trending Technologies
Technical articles with clear explanations and examples
Extract key value from a nested object in JavaScript?
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 MoreSleep in JavaScript delay between actions?
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=30
Read MoreReturn Largest Numbers in Arrays passed using reduce method?
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 ]
Read MoreRemove characters from a string contained in another string with JavaScript?
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
Read MoreUn-nesting array of object in JavaScript?
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 MoreRemove extra spaces in string JavaScript?
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 MoreHow to modify key values in an object with JavaScript and remove the underscore?
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' }
Read MoreRemove '0','undefined' and empty values from an array in JavaScript
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 MoreDisplay all the numbers from a range of start and end value in JavaScript?
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, 19
Read MoreHow could I write a for loop that adds up all the numbers in the array to a variable in JavaScript?
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 ...
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