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ProblemYou need to identify the most frequently occurring items in a sequence.SolutionWe can use counter to keep track of the items in a sequence.What is a Counter ?The “Counter” is a mapping that holds an integer count for each key. Updating an existing key adds to its count. This Objectis used for counting the instances of hashable objects or as a multiset.The “Counter” is one of your best friends when you are performing data analysis.This object has been present in Python for quite some time, and so for a lot of you, this will be a quick review.We will start ... Read More
For this, use Object.keys() along with reduce(). To display the result, we will also use concat().ExampleFollowing is the code −var details = { name: ["John", "David"], age1: "21", age2: "23" }, output = Object .keys(details) .reduce((obj, tempKey) => (obj[tempKey] = [].concat(details[tempKey]), obj), {}) console.log(output) To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo302.js.OutputThis will produce the following output on console −PS C:\Users\Amit\javascript-code> node demo302.js { name: [ 'John', 'David' ], age1: [ '21' ], age2: [ '23' ] }
Let’s say we have marks records and we need to sum them. The records are displayed in Radio Button −Marks1 75 { if (evnt.checked) { total = total + parseInt(evnt.value); return; } }); secondMark.forEach((evnt) => { if (evnt.checked) { total = total + parseInt(evnt.value); return; } }); ... Read More
Let’s say the following is our array −var values = [7,5,3,8,9,'/',9,5,8,2,'/',3,4,8];To merge specific elements, use map along with split().ExampleFollowing is the code −var values = [7,5,3,8,9,'/',9,5,8,2,'/',3,4,8]; var afterMerge = values.join('') .split(/(\d+)/). filter(Boolean). map(v => isNaN(v) ? v : +v); console.log(afterMerge);To run the above program, you need to use the following command −node fileName.js. Here, my file name is demo301.js.OutputThis will produce the following output on console −PS C:\Users\Amit\javascript-code> node demo301.js [ 75389, '/', 9582, '/', 348 ]
For this, you can use ternary operator based on some condition.ExampleFollowing is the code −const yearRangeValue = 18; const getCorrectCentury = dateValues => { var [date, month, year] = dateValues.split("-"); var originalYear = +year > yearRangeValue ? "20" + year : "18" + year; return new Date(date + "-" + month + "-" + originalYear).toLocaleDateString('en-GB') }; console.log(getCorrectCentury('10-JAN-19'));To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo300.js.OutputThis will produce the following output on console −PS C:\Users\Amit\javascript-code> node demo300.js 1/10/2019
The get keyword can be used as a getter function like C#, Java and other technologies.We set a function with get like the following in a class −class Employee { constructor(name) { this.name = name; } get fullName() { return this.name; } }ExampleFollowing is the code displaying an example of get −class Employee { constructor(name) { this.name = name; } get fullName() { return this.name; } } var employeeObject = new Employee("David Miller"); console.log(employeeObject.fullName);To run the above program, you need to use ... Read More
We are required to write a JavaScript function that takes in two 2-D arrays of numbers and returns their matrix multiplication result.Let’s say the following are our two matrices −// 5 x 4 let a = [ [1, 2, 3, 1], [4, 5, 6, 1], [7, 8, 9, 1], [1, 1, 1, 1], [5, 7, 2, 6] ]; // 4 x 6 let b = [ [1, 4, 7, 3, 4, 6], [2, 5, 8, 7, 3, 2], [3, 6, 9, 6, 7, 8], [1, 1, 1, 2, 3, 6] ];ExampleLet’s ... Read More
We are required to write a JavaScript function that takes in a string and any number of characters specified as separators. Our function should return a splitted array of the string based on all the separators specified.For example −If the string is −const str = 'rttt.trt/trfd/trtr, tr';And the separators are −const sep = ['/', '.', ', '];Then the output should be −const output = [ 'rttt', 'trt', 'trfd', 'trtr' ];ExampleFollowing is the code −const str = 'rttt.trt/trfd/trtr, tr'; const splitMultiple = (str, ...separator) => { const res = []; let start = 0; for(let i = 0; ... Read More
Introduction..MMAP abbreviated as memory mapping when mapped to a file uses the operating systems virtual memory to access the data on the file system directly, instead of accessing the data with the normal I/O functions. There by improving the I/O performance as it does not require either making a separate system call for each access or copying data between buffers.To a matter of fact anything in memory for instance a SQLlite database when created in-memeory has better performance compared to on disk.Memory-mapped files can be treated as mutable strings or file-like objects, depending on what you want to do.MMAP supports ... Read More
Given an array of integers, we are required to write a function that takes this array and finds the one element that appears an odd number of times. There will always be only one integer that appears an odd number of times.We will approach this problem by sorting the array. Once sorted, we can iterate over the array to pick the element that appears for odd number of times.ExampleFollowing is the code −const arr = [20, 1, -1, 2, -2, 3, 3, 5, 5, 1, 2, 4, 20, 4, -1, -2, 5]; const findOdd = arr => { let ... Read More