如何避免循环重复？

Question

There is a specific logic for filtering collection:

    let rows = (collection || []).filter((item: any) => {
      const { country, year, productType, units, productSubtype } = item;
      const cond1 = unitsPlain.length ? unitsPlain.includes(units) : true;
      const cond3 = years.includes(year);
      const cond2 = country === value;
      const cond4 = productType === key && !productSubtype;

      return cond1 && cond2 && cond3 && cond4;
    });

    if (!rows.length) {
      rows = collection.filter((item: any) => {
        const { country, year, productType, productSubtype } = item;
        const cond3 = years.includes(year);
        const cond2 = country === value;
        const cond4 = productSubtype === key && !productType;

        return cond2 && cond3 && cond4;
      });
    }

    if (!rows.length) {
      rows = collection.filter((item: any) => {
        const { country, year, productType, productSubtype } = item;
        const cond3 = years.includes(year);
        const cond2 = country === value;
        const cond4 = productSubtype === key || productType === key;

        return cond2 && cond3 && cond4;
      });
    }

As you noticed I try to launch the next loop to find elements of prev returns empty result.

How to improve it?

Answer 1

You can chain filters

let rows = (collection || []).filter(callbackFn).filter(callbackFn)