Javascript Articles - Page 265 of 534

To check the value for percentage, use a regular expression. When dealing with user input or processing data in JavaScript, it's important to make sure a value is a valid percentage. This article shows you how to check if a value is a percentage using JavaScript, highlighting a useful method that involves regular expressions. Let's say the following is our value var value="97%"; To check the value for percentage, we are using a regular expression. Using Regular Expression The best way to check if a string is in the correct percentage format is by using regular expressions. ... Read More

To store large numbers in JavaScript, use BigInt() rather than + operator. If you will use the + operator, then expect loss of precision.Let’s say the following is our large number and we are storing using BigInt() −console.log("Loss of precision with + operator..")ExampleFollowing is the code −var stringValue1="100"; console.log("The integer value="); console.log(+stringValue1); var stringValue2="2312123211345545367"; console.log("Loss of precision with + operator..") console.log(+stringValue2); const storeLongInteger=BigInt("2312123211345545367"); console.log("No loss of precision with BigInt()"); console.log(storeLongInteger);To run the above program, you need to use the following command −node fileName.js. Here, my file name is demo212.js.OutputThe output is as follows on console −PS C:\Users\Amit\JavaScript-code> node demo213.js The ... Read More

Let's say the following is our JSON string −var details = [    {       customerName: "Chris",       customerAge: 32    },    {       customerName: "David",       customerAge: 26    },    {       customerName: "Bob",       customerAge: 29    },    {       customerName: "Carol",       customerAge: 25    } ]To remove JSON element, use the delete keyword in JavaScript.ExampleFollowing is the complete code to remove JSON element −var details = [    {       customerName: "Chris",       ... Read More

Suppose we have an array that contains some dates like this −const arr = [    [ '02/13/2015', 0.096 ],    [ '11/15/2013', 0.189 ],    [ '05/15/2014', 0.11 ],    [ '12/13/2013', 0.1285 ],    [ '01/15/2013', 0.12 ],    [ '01/15/2014', 0.11 ],    [ '02/14/2014', 0.11 ],    [ '03/14/2014', 0.11 ],    [ '01/15/2015', 0.096 ],    [ '07/15/2015', 0.096 ],    [ '04/15/2013', 0.12 ],    [ '04/15/2014', 0.11 ],    [ '05/15/2013', 0.12 ],    [ '06/14/2013', 0.12 ],    [ '06/16/2014', 0.11 ],    [ '07/15/2013', 0.12 ],    [ '07/15/2014', 0.11 ], ... Read More

We are required to write a JavaScript function that takes in an array of strings and returns an object corresponding to the strings.For example −If the array is −const arr = [    "country.UK.level.1",    "country.UK.level.2",    "country.US.level.1",    "country.UK.level.3" ];Then the output should be −const output = {    "country": [        {"UK" : {"level" : ["1", "2", "3"]}},        {"US" : {"level" : ["1", "2"]}}   ] } ConditionsStrings stored in the str array will not be sorted and the code should be robust against that.Strings will follow the x.y.x.y... pattern, where x will be ... Read More

We are required to write a JavaScript function that takes in an array of strings. The function should join all the strings of the array, replace all the whitespaces with dash "-", and return the string thus formed.For example: If the array is −const arr = ["QA testing promotion ", " Twitter  ", "Facebook ", "Test"];Then the output should be −const output = "QA-testing-promotion-Twitter-Facebook-Test";ExampleFollowing is the code −const arr = ["QA testing promotion ", " Twitter ", "Facebook ", "Test"]; const joinArr = arr => {    const arrStr = arr.join('');    let res = '';    for(let i = ... Read More

Given an array X of multiple values (e.g. [-3, 5, 1, 3, 2, 10]), We are required to write a function that removes any negative values in the array.Once the function finishes its execution the array should be composed of just positive numbers. We are required to do this without creating a temporary array and only using pop method to remove any values in the array.ExampleFollowing is the code −// strip all negatives off the end while (x.length && x[x.length - 1] < 0) {    x.pop(); } for (var i = x.length - 1; i >= 0; i--) { ... Read More

We are required to write a JavaScript function that takes in an array that contains some numbers, some strings and some falsy values.Our function should return the biggest Number from the array.For example −If the input array is the following with some undefined values −const arr = [23, 'hello', undefined, null, 21, 65, NaN, 1, undefined, 'hii'];Then the output should be 65ExampleFollowing is the code −const arr = [23, 'hello', undefined, null, 21, 65, NaN, 1, undefined, 'hii']; const pickBiggest = arr => {    let max = -Infinity;    for(let i = 0; i < arr.length; i++){     ... Read More

We are required to write a JavaScript function that takes in an array of Numbers.The function should return the middlemost element of the array.For example −If the array is −const arr = [1, 2, 3, 4, 5, 6, 7];Then the output should be 4ExampleFollowing is the code −const arr = [1, 2, 3, 4, 5, 6, 7]; const middle = function(){    const half = this.length >> 1;    const offset = 1 - this.length % 2;    return this.slice(half - offset, half + 1); }; Array.prototype.middle = middle; console.log(arr.middle()); console.log([1, 2, 3, 4, 5, 6].middle());OutputThis will produce the following output on console −[ 4 ] [ 3, 4 ]

We are required to write a JavaScript function that takes in an array of literals and returns a new array that have elements of the original array chunked into subarrays of length exactly 2.Now if the length of original array is not exactly divisible by 2, then the last subarray should have only one element.For example, If the input array is −const arr = [1, 2, 3, 4, 5, 6, 7];Then the output should be −const output = [[1, 2], [3, 4], [5, 6], [7]]ExampleFollowing is the code −const arr = [1, 2, 3, 4, 5, 6, 7]; const chunk ... Read More