It then adjusts the date to the Thursday of the same week, which is always in the same ISO week as the input date. It first calculates the day of the week (1-7) of the input date in UTC time, where Monday is 1 and Sunday is 7. This function takes a Date object as input and returns the ISO week number as an integer. javascriptĬonst dayOfWeek = date.getUTCDay() || 7 // Monday = 1, Sunday = 7ĭate.setUTCDate(date.getUTCDate() + 4 - dayOfWeek) // Thursday of the current weekĬonst yearStart = new Date(Date.UTC(date.getUTCFullYear(), 0, 1)) This is the most widely used definition of the week number. The ISO week numbering system defines the first week of the year as the week containing January 4th, and the week starting on Monday. Here is a comprehensive solution that takes into account different definitions of the week number: There are different ways to get the current week number in JavaScript, depending on how you define what the first week of the year is and what day of the week it starts on. Programming Language: JavaScript, Popularity : 6/10 Look at the below screenshot where the HTML form having an input field of Calendar type and one submit button to perform all the calculations and one more field to display calculated results.Answered on: Wed / Duration: 5-10 min read Javatpoint: Calculate Week Number using user input Return document.getElementById("result").innerHTML = "Week number of given date is: " + result return the calculated result and display it
Var result = Math.ceil(( date1.getDay() + 1 + numberOfDays) / 7) adding 1 since to current date and returns value starting from 0 calculating number of days in given year before the given date Var oneJan = new Date(date1.getFullYear(), 0, 1) create a date object variable to store the date values Var dateinput = document.getElementById("dateInput1").value define a variable and fetch the input from HTML form Now, we will convert these steps into actual implementation. Finally, display the calculated weekday on the web using document.write().Don't forget to put this whole calculation of step 6 inside Math.ceil() method. Now, add 1 and numberofdays calculated in previous result to the day of current date and divide them by 7, i.e., (this.getDay() + 1 + numberofdays) / 7.So, calculate the difference of current date and current year date and divide it by total milliseconds in a day (1000*60*60*24). After getting the current date and year, now calculate the number of days using the Math.floor() method.The getFullYear() function will return the year of current date along with first date of the year, e.g.Initialize another variable oneJan by creating date object using new Date() but this time getFullYear() method inside it.
Initialize the todaydate variable by creating the date object using new Date(), which will take system date by default.Define a date variable todaydate and oneJan in JavaScript.Follow each step for calculating weekdays: It is a static way to calculate the week number. In this approach, we will find the week number of current date means the date will be taken from the system. Calculate the week number by taking date input dynamic HTML formĪpproach 1: Calculate Week Number of current date.Along with that, we will calculate the weekdays dynamically by taking date input from the user using a dynamic HTML form. We will discuss both the methods in detail with examples. Calculate the week number for a predefined date.Calculate the week number of the current date.We will calculate the week number in two ways: We can use this concept in our JavaScript example to calculate the week number.
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