Javascript Articles

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How do I make an array with unique elements (remove duplicates) - JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 249 Views

Let’s say the following is our array with duplicate elements −var duplicateNumbers = [10, 20, 100, 40, 20, 10, 100, 1000];We want the output to be −[10, 20, 100, 40, 1000];To display only the unique elements, use the concept of filter.ExampleFollowing is the code −var duplicateNumbers = [10, 20, 100, 40, 20, 10, 100, 1000]; console.log("With Duplicates Values="); console.log(duplicateNumbers); var noDuplicateNumbersArray = duplicateNumbers.filter(function (value, index, array) {     return array.indexOf(value) === index; } ); console.log("Without Duplicates Values=") console.log(noDuplicateNumbersArray);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo234.js.OutputThe output is as ...

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Comparing adjacent element and swap - JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 441 Views

This is the concept of Bubble Sort. It compares to adjacent element if it is lesser it will swap the value.ExampleFollowing is the code −var numbers = [10, 100, 30, 40, 90, 4, 91, 56, 78]; function bubbleSorting(numbers) {    for (var outer = 0; outer < numbers.length; outer++) {       for (var inner = 0; inner < numbers.length; inner++) {          if (numbers[outer] < numbers[inner]) {             var temp = numbers[outer];             numbers[outer] = numbers[inner];             numbers[inner] = temp; ...

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Number prime test in JavaScript by creating a custom function?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 202 Views

Create a custom function to test a number is prime or not in JavaScript.ExampleFollowing is the code −function checkNumberIsPrime(number) {    var flag = false;    for (start = 2; start < number / 2; start++) {       if (number % start === 0) {          flag = false;             break;       }       else {          flag = true;       }    }    return flag; } var number = 11; if (checkNumberIsPrime(number) == true) {    console.log("The number is prime"); } else {    console.log("The number is not prime"); }To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo230.js.OutputThe output is as follows −PS C:\Users\Amit\JavaScript-code> node demo230.js The number is prime

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Display the result difference while using ceil() in JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 179 Views

The Math.ceil() is part of the Math object in JavaScript. Suppose, your value is 4.5 or 4.3, it will give the result 5.Let’s say the following are our values −var result1 = 98; var result2 = 5;Following is the code to display the result difference while using ceil() or not −var result1 = 98; var result2 = 5; console.log("The actual result is=" + result1 / result2); var output = Math.ceil(result1 / result2); console.log("The ceil result is=" + output);To run the above program, you need to use the following command −node fileName.js. Here, my file name is demo229.js.OutputThe output is as ...

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Remove/ filter duplicate records from array - JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 291 Views

Let’s say the following are our records with some duplicate values −var objectOfNationality =    [       { nationality: "Indian" },       { nationality: "American" },       { nationality: "Emirati" },       { nationality: "Indian" },       { nationality: "American" }    ];ExampleTo remove duplicate records, use the concept of Set().Following is the code −var objectOfNationality =    [       { nationality: "Indian" },       { nationality: "American" },       { nationality: "Emirati" },       { nationality: "Indian" },       ...

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How do I turn a string in dot notation into a nested object with a value &ndash; JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 4K+ Views

Let’s say the following is our string in dot notation −const keys = "details1.details2.details3.details4.details5"And the following is our array −const firsName = "David";To turn into a nested object, use the concept of split(‘.’) along with map().ExampleFollowing is the code −const keys = "details1.details2.details3.details4.details5" const firsName = "David"; var tempObject = {}; var container = tempObject; keys.split('.').map((k, i, values) => {    container = (container[k] = (i == values.length - 1 ? firsName : {})) }); console.log(JSON.stringify(tempObject, null, ' '));To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo227.js.OutputThe output is as ...

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Variable defined with a reserved word const can be changed - JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 163 Views

You cannot change the value of an object when it is defined using const keyword.After changing it will remain same.Let’s say the following is our variable defined with const −const details1 = {    firstName: 'David',    subjectDetails: { subjectName: 'JavaScript' } }ExampleFollowing is the code to change the const variable, which would only display the initial value −const details1 = {    firstName: 'David',    subjectDetails: { subjectName: 'JavaScript' } } const details2 = { ...details1, subjectDetails: { ...details1.subjectDetails }, firstName: 'David' } details2.subjectDetails.subjectName = 'Java ' console.log(details1);To run the above program, you need to use the following command ...

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Object comparison Complexity in JavaScript using comparison operator or JSON.stringlify()?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 202 Views

Let’s say the following are our objects −var object1 = { firstName: "David" }; var object2 = { firstName: "David" };You will not get the correct result using comparison operator (== or ===). Use JSON.stringify() for this.ExampleFollowing is the code implementing both the ways and showing the correct result −var object1 = { firstName: "David" }; var object2 = { firstName: "David" }; if (object1 == object2)    console.log("using == operator result ==> true"); else    console.log("using == operator result ==> false"); if (JSON.stringify(object1) == JSON.stringify(object2))    console.log("using JSON.stringify() operator result ==> true"); else    console.log("using JSON.stringify() operator result ==> ...

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Fetch specific values from array of objects in JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 2K+ Views

Let’s say the following are our array of objects:const details =    [       {          employeeFirstName: "John",          employeeLastName: "Doe"       },       {          employeeFirstName: "David",          employeeLastName: "Miller"       },       {          employeeFirstName: "John",          employeeLastName: "Smith"       }    ]ExampleFollowing is the code to fetch specific values, in this case with first name “John” −const details =    [       {     ...

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How to allocate memory to an object whose length is set to 0 - JavaScript?

AmitDiwan
AmitDiwan
Updated on 03-Oct-2020 125 Views

Let’s say the following is our array object −var arrayObject =    [       "John",       "David",       "Mike"    ]Use length property to set the length to 0 and clear memory.The syntax is as follows to clear memory and allocate again −yourArrayObjectName.length=0; // To clear memory yourArrayObjectName.length=4; // To allocate memoryExampleFollowing is the code −var arrayObject =    [       "John",       "David",       "Mike"    ] arrayObject.length = 0; console.log(arrayObject); arrayObject.length = 5; for (var i = 0; i < arrayObject.length; i++)    console.log(arrayObject[i]);To run the ...

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