WEEKNUM function

PRO BASIC

In Jspreadsheet Formulas Pro, the WEEKNUM function is used to determine the week number of a specific date. When you input a date into this function, it calculates and returns the week number, based on the calendar year. This can be particularly useful for tracking activities or events that occur on a weekly basis. It's a simple and effective tool for organizing your data by week.

Documentation

Returns the week number of a given date.

Syntax

WEEKNUM(serial_number, [return_type])

Parameter	Description
`serial_number`	The serial number that represents the date whose week number you want to find.
`[return_type]`	Optional. A number that determines the type of return value:
1 (or omitted): Week starts on Sunday; week 1 is the week containing January 1
2: Week starts on Monday; week 1 is the week containing January 1
11–16: Define which day is considered the start of the week (Monday = 11, Tuesday = 12, …, Saturday = 16) with week 1 starting January 1
21: ISO standard – Week starts on Monday; week 1 is the first week with at least 4 days in the new year

Behavior

The WEEKNUM function in spreadsheets is used to return the week number of a specific date. The weeks can begin on either Sunday or Monday, depending on the optional second argument provided. Here's how it handles different types of inputs:

Empty Cells: If the WEEKNUM function references an empty cell, it will return a #VALUE! error.
Text: If the cell referenced contains text that cannot be interpreted as a date, the function will return a #VALUE! error.
Booleans: The WEEKNUM function does not work with boolean values. If a cell containing a boolean value is referenced, the function will return a #VALUE! error.
Errors: If the cell referenced in the function contains an error, the WEEKNUM function will also return that same error.
Numbers: If the cell referenced contains a number, the WEEKNUM function will treat that number as a date serial number and return the corresponding week number.

Common Errors

Error	Description
#VALUE!	This error occurs if the provided date is not a valid date or if it is a text that cannot be interpreted as a date.
#NUM!	This error is returned when the second argument (indicating the week starting day) is not within the acceptable range of 1 to 21.

Best practices

Always ensure that the cell reference or date provided to the WEEKNUM function is a valid date to avoid a #VALUE! error.

Be careful when providing the second argument to the WEEKNUM function. Make sure it is within the acceptable range (1 to 21) to avoid a #NUM! error.

When referencing a cell, ensure it does not contain text or boolean values as WEEKNUM cannot interpret these and will return a #VALUE! error.

Be aware that the WEEKNUM function will consider a number as a date serial number. If this is not the desired outcome, make sure to convert numbers to the appropriate date format before using them in the function.

Usage

A few examples using the WEEKNUM function.

WEEKNUM("2015-01-04")  
// Returns: 2 (Sunday, week starting January 1 with return_type = 1)

WEEKNUM("2015-01-04", 2)  
// Returns: 1 (week starts Monday, January 1 in week 1)

WEEKNUM("1900-01-02")  
// Returns: 1 (January 2, 1900 falls in week 1)

WEEKNUM(42008)  
// Returns: 2 (numeric serial interpreted as 2015-01-05)

WEEKNUM("2023-01-05", 21)  
// Returns: 1 (ISO standard, week starts Monday, first week with 4 days in year)

Interactive Spreadsheet Demo

<html>
<script src="https://jspreadsheet.com/v11/jspreadsheet.js"></script>
<script src="https://jsuites.net/v5/jsuites.js"></script>
<link rel="stylesheet" href="https://jsuites.net/v5/jsuites.css" type="text/css" />
<link rel="stylesheet" href="https://jspreadsheet.com/v11/jspreadsheet.css" type="text/css" />

<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Material+Icons" />
<script src="https://cdn.jsdelivr.net/npm/@jspreadsheet/formula-pro/dist/index.min.js"></script>

<div id="spreadsheet"></div>

<script>
// Set your JSS license key (The following key only works for one day)
jspreadsheet.setLicense('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');

// Set the extensions
jspreadsheet.setExtensions({ formula });

// Create a new spreadsheet
jspreadsheet(document.getElementById('spreadsheet'), {
  worksheets: [{
    data: [
    [
        "Date",
        "Week Number"
    ],
    [
        "2024-01-15",
        "=WEEKNUM(A2)"
    ],
    [
        "2024-06-30",
        "=WEEKNUM(A3)"
    ],
    [
        "2024-12-25",
        "=WEEKNUM(A4)"
    ]
]
  }]
});
</script>
</html>

import React, { useRef } from "react";
import { Spreadsheet, Worksheet, jspreadsheet } from "@jspreadsheet/react";
import formula from "@jspreadsheet/formula-pro";
import "jsuites/dist/jsuites.css";
import "jspreadsheet/dist/jspreadsheet.css";

// Set license
jspreadsheet.setLicense('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');

// Set the extensions
jspreadsheet.setExtensions({ formula });

export default function App() {
    // Spreadsheet array of worksheets
    const spreadsheet = useRef();

    // Worksheet data
    const data = [
    [
        "Date",
        "Week Number"
    ],
    [
        "2024-01-15",
        "=WEEKNUM(A2)"
    ],
    [
        "2024-06-30",
        "=WEEKNUM(A3)"
    ],
    [
        "2024-12-25",
        "=WEEKNUM(A4)"
    ]
];

    // Render component
    return (
        <Spreadsheet ref={spreadsheet}>
            <Worksheet data={data} />
        </Spreadsheet>
    );
}

<template>
    <Spreadsheet ref="spreadsheet">
        <Worksheet :data="data" />
    </Spreadsheet>
</template>

<script>
import { Spreadsheet, Worksheet, jspreadsheet } from "@jspreadsheet/vue";
import "jsuites/dist/jsuites.css";
import "jspreadsheet/dist/jspreadsheet.css";
import formula from "@jspreadsheet/formula-pro";

// Set license
jspreadsheet.setLicense('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');

// Set the extensions
jspreadsheet.setExtensions({ formula });

export default {
    components: {
        Spreadsheet,
        Worksheet,
    },
    data() {
        // Worksheet data
        const data = [
    [
        "Date",
        "Week Number"
    ],
    [
        "2024-01-15",
        "=WEEKNUM(A2)"
    ],
    [
        "2024-06-30",
        "=WEEKNUM(A3)"
    ],
    [
        "2024-12-25",
        "=WEEKNUM(A4)"
    ]
]

        return {
            data
        };
    }
}
</script>

import { Component, ViewChild, ElementRef } from "@angular/core";
import jspreadsheet from "jspreadsheet";
import * as formula from "@jspreadsheet/formula-pro";

// Set your JSS license key (The following key only works for one day)
jspreadsheet.setLicense('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');

// Set the extensions
jspreadsheet.setExtensions({ formula });

@Component({
    standalone: true,
    selector: "app-root",
    template: `<div #spreadsheet></div>`
})
export class AppComponent {
    @ViewChild("spreadsheet") spreadsheet: ElementRef;
    // Worksheets
    worksheets: jspreadsheet.worksheetInstance[];

    // Create a new data grid
    ngAfterViewInit() {
        // Create spreadsheet
        this.worksheets = jspreadsheet(this.spreadsheet.nativeElement, {
            worksheets: [{
                data: [
    [
        "Date",
        "Week Number"
    ],
    [
        "2024-01-15",
        "=WEEKNUM(A2)"
    ],
    [
        "2024-06-30",
        "=WEEKNUM(A3)"
    ],
    [
        "2024-12-25",
        "=WEEKNUM(A4)"
    ]
]
            }]
        });
    }
}

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