undefined (reading 'valueOf') finding the number of the week in Vue-CodePudding

I am trying to find the number of the week. So for this my function is:

getWeekNumber(date) {
            const temp_date = new Date(date.valueOf());
            const dayn = (date.getDay()   6) % 7;
            temp_date.setDate(temp_date.getDate() - dayn   3);
            const firstThursday = temp_date.valueOf();
            temp_date.setMonth(0, 1);
            if (temp_date.getDay() !== 4) {
                temp_date.setMonth(0, 1   ((4 - temp_date.getDay()   7) % 7));
            }
            return 1   Math.ceil((firstThursday - temp_date) / 604800000);
        },

And I am using this function in my other function to find the products:

findProducts(products, date) {
            return products.filter((product) => {
                const formated_date = this.setDateFormat(product.attributes.date);
                console.log(formated_date);
                console.log(formated_date.valueOf());
                return (
                    formated_date.getDate() === date.getDate() &&
                    formated_date.getMonth() === date.getMonth() &&
                    formated_date.getFullYear() === date.getFullYear() &&
                    this.getWeekNumber(formated_date) === this.currentWeekNumber
                );
            });
        },

But my problem is inside of the findProducts function in console I can see the output like this: Tue Sep 28 2021 02:00:00 GMT 0200 (Central European Summer Time) Table.vue:144 1632787200000

But whenever it goes to getWeekNumber function I am getting this error: vue.esm.js:1897 TypeError: Cannot read properties of undefined (reading 'valueOf')

Do you have any idea why it can be?

Thanks...

CodePudding user response：

It is never a good idea to implement date related concepts yourself. There is so many caveats that you dont know about. I recommend using something like Day.js

Specifically Week of Year

CodePudding user response：

Maybe the problem here are the scopes, lambdas remove "this" object, for example:

const test = {
  x : "hello",
  lambda: () => this.x,
  fun: function () { return this.x}
}


console.log(test.lambda()) //undefined
console.log(test.fun()) //"hello"

To solve this you can wrap your "this" object inside another object, for example:

findProducts(products, date) {
            let vueThis = this
            return products.filter((product) => {
                const formated_date = this.setDateFormat(product.attributes.date);
                console.log(formated_date);
                console.log(formated_date.valueOf());
                return (
                    formated_date.getDate() === date.getDate() &&
                    formated_date.getMonth() === date.getMonth() &&
                    formated_date.getFullYear() === date.getFullYear() &&
                    vueThis.getWeekNumber(formated_date) === vueThis.currentWeekNumber
                );
            });
        },

With this approach you are using "this" context from vue inside your lambda, also you can change this to an anonymous function and call it later.