Get data from the function based on the type passed without using if-else or switch

Question

I want to get the variables values based on the parameter passed to the function. Is there any way to do this:

 getDaysInCurrentMonth(type = 'all') {
      const date = new Date(),
            month = date.getMonth(),
            year = date.getFullYear(),
            days = new Date(year, month, 0).getDate();
      if (type === 'all') return { date, month, year, days };
      return [type];
  }

For example, if I pass days in the getDaysInCurrentMonth('days'), it should only return days. Is there any way to do this?

What is the problem of putting them in an object and get them by property name? — VLAZ, Aug 20 '21 at 11:10
@VLAZ, yes we can do that and it can be done which is what I was thinking. But I wanted to know is it in any way possible to get the variables values using type param. — Apoorva Chikara, Aug 20 '21 at 11:37
@ApoorvaChikara then you are asking for [“Variable” variables in JavaScript](https://stackoverflow.com/q/5187530). Which is not possible (outside of `eval` which you shouldn't use and don't need to use). And the accepted answer there does show that it's much easier with an object. — VLAZ, Aug 20 '21 at 11:38

score 1 · Accepted Answer · answered Aug 20 '21 at 11:07

If you want to return a single parameter, you could create an object and then access it by key. For example

getDaysInCurrentMonth(type = 'all') {
  const date = new Date(),
        month = date.getMonth(),
        year = date.getFullYear(),
        days = new Date(year, month, 0).getDate();
  const result = { date, month, year, days };
  if (type === 'all') return result;
  else return result[type];
}

You would have to be sure to only call the method with the specified types or add error handling though.

Yes, definitely I can do that, but why to create another space and then use it. cant we send the variables values directly? — Apoorva Chikara, Aug 20 '21 at 11:34

score 1 · Answer 2 · answered Aug 20 '21 at 11:13

You can do something like this.

getDaysInCurrentMonth(type = 'all') {
  const date = new Date(),
        month = date.getMonth(),
        year = date.getFullYear(),
        days = new Date(year, month, 0).getDate();
  const result = { date, month, year, days };
  return (type === 'all') ? result : result[type]
}

score 0 · Answer 3 · answered Aug 20 '21 at 11:09

Yes, there is.

Your end function should look something like this:

const getDaysInCurrentMonth = (type = 'all') => {
     const date = new Date(),
            month = date.getMonth(),
            year = date.getFullYear(),
            days = new Date(year, month, 0).getDate();
    switch(type){
        case "all": return { date, month, year, days };
        case "month": return { month };
        case "date": return { date };
        case "year": return { year };
        default: return `Unknown type ${type}`;
    }
}

The OP question clearly states "*without using if-else or switch*" — secan, Aug 20 '21 at 11:10

ahsan · Answer 4 · 2021-08-20T11:19:43.143

0

You can try using a dictionary and save your values in Key-Value pairs where key is the parameter you accept as an argument to the function.

function getDaysInCurrentMonth(type = 'all') {
            const obj = {};
      const date = new Date;
      const month = date.getMonth();
      const year = date.getFullYear();
      
        obj["date"] = date;
      obj["month"] = month;
      obj["year"] = year;
      obj["days"] = new Date(year, month, 0).getDate();
      
      return obj[type] || date.toLocaleString();

  }
 
 console.log(getDaysInCurrentMonth("year"));
 console.log(getDaysInCurrentMonth("month"));
 console.log(getDaysInCurrentMonth("days"));

edited Aug 20 '21 at 11:19

answered Aug 20 '21 at 11:11

ahsan

1,409
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11

It does not look very DRY; if you have `const month = date.getMonth();` then you can do `obj["month"] = month;`, there is no point in doing `obj["month"] = date.getMonth();` and why should you generate a `new Date` to give a value to `obj["days"]`, when yu already have `date`? – secan Aug 20 '21 at 11:16
@secan I have simply used the provided code by the OP. I wanted to provide a solution with minimum modifications so its easier to understand. – ahsan Aug 20 '21 at 11:24

Get data from the function based on the type passed without using if-else or switch

4 Answers4

Yes, there is.