Print all even values in all object key end with odd value-CodePudding

I want to print all even values in all object key end with odd value but the coding I made just now is only specified for arr1, arr3, and arr5. Can anyone suggest me how to fix 'let oddArr' method (maybe in loop) so that when I changed arr1 into arr7, the result would be the same.

var num = {
    arr1 : [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
    arr2 : [11, 12, 13, 14, 15, 16, 17, 18, 19, 20],
    arr3 : [21, 22, 23, 24, 25, 26, 27, 28, 29, 30],
    arr4 : [31, 32, 33, 34, 35, 36, 37, 38, 39, 40],
    arr5 : [41, 42, 43, 44, 45, 46, 47, 48, 49, 50],
    };

    let oddArr = [...num.arr1, ...num.arr3, ...num.arr5] //need some correction here
    let evenNum = oddArr.filter(number => number % 2 == 0);

    console.log(evenNum.toString());
    
    //help me fix 'let oddArr' (maybe in loop method) so that when I changed the object of the array (e.g: arr1 -> arr7) it would come out with the same result 
    
    //the result/output should be 2,4,6,8,10,22,24,26,28,30,42,44,46,48,50 based on var num

CodePudding user response：

You can try like below using for in loop and it works with any last character as odd.

var num = {
  arr1: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
  arr2: [11, 12, 13, 14, 15, 16, 17, 18, 19, 20],
  arr3: [21, 22, 23, 24, 25, 26, 27, 28, 29, 30],
  arr4: [31, 32, 33, 34, 35, 36, 37, 38, 39, 40],
  arr7: [41, 42, 43, 44, 45, 46, 47, 48, 49, 50]
};

let oddArr = [];
for (let key in num) {
  if (key.charAt(key.length - 1) % 2 !== 0) {
    oddArr = [...oddArr, ...num[key]];
  }
}

let evenNum = oddArr.filter((number) => number % 2 === 0);

console.log(evenNum.toString());

CodePudding user response：

You might want to use

let oddArr = Object.entries(num).filter(   // filter key names
   e =>  e[0].replace("arr", '') % 2 !== 0 // replace "arr" and check if X in arrX is odd
).map(e => e[1]).flat()                    // merge values and flattern array

You can also make use of regex if the "arrX"-naming is not consistent:

 e[0].match(/\d /) % 2 !== 0

See a working snippet below:

var num = {
  arr1: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
  arr2: [11, 12, 13, 14, 15, 16, 17, 18, 19, 20],
  arr3: [21, 22, 23, 24, 25, 26, 27, 28, 29, 30],
  arr4: [31, 32, 33, 34, 35, 36, 37, 38, 39, 40],
  arr5: [41, 42, 43, 44, 45, 46, 47, 48, 49, 50],
};

let oddArr = Object.entries(num).filter(
  e =>  e[0].replace("arr", '') % 2 !== 0
).map(e => e[1]).flat()

let evenNum = oddArr.filter(number => number % 2 == 0);
console.log(evenNum.toString());

CodePudding user response：

This also works.

var num = {
  arr1: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
  arr2: [11, 12, 13, 14, 15, 16, 17, 18, 19, 20],
  arr3: [21, 22, 23, 24, 25, 26, 27, 28, 29, 30],
  arr4: [31, 32, 33, 34, 35, 36, 37, 38, 39, 40],
  arr5: [41, 42, 43, 44, 45, 46, 47, 48, 49, 50],
  arr6: [51, 52, 53, 55, 55, 56, 57, 58, 59, 60],
  arr7: [61, 62, 63, 66, 65, 66, 67, 68, 69, 70],
};

var evenNums = Object.keys(num).filter((item) => {
    itemNum = item.replace("arr", "");
    return itemNum % 2 !== 0;
}).map((o) => num[o]).flat().filter((x) => x % 2 == 0);

console.log(evenNums);