遍历并使用相同的代码访问数组和对象元素

Question

Let's say I have a function that receives either an object or an array. I would like to iterate through each element, and do something to each element as I go. I know that I can iterate through an array with forEach() or a normal for loop. I can also iterate through an object and array with a for in loop . But unlike the array case I have to check the object's elements with hasOwnProperty() .

Can I just apply some general piece of code to both arrays and objects?

Update. This is my attempt for some object/array called value, but no console messages appear for the object case:

keysArray = Object.keys(value);
for(let key in keysArray) {
    console.log(value[key])
}

Answer 1

You could use

function* entries(o) {
    if (Array.isArray(o))
        for (let i=0; i<o.length; i++)
            yield [i, o[i]];
    else
        for (const p in o)
            yield [p, o[i]];
}
// or using builtin iterators:
function entries(o) {
    return Array.isArray(o) ? o.entries() : Object.entries(o).values();
}

and call it as

for (const [key, value] of entries(something)) {
    console.log(key, value);
}

Of course you can do a similar thing to get just the keys or just the values.

Answer 2

// whatever can be object or array

function doSth(whatever) {
  let myLoopable = whatever;

  // obj to array
  if (!Array.isArray(whatever)) {
    myLoopable = Object
      .keys(whatever) // get array of keys
      .reduce((acc, curKey) => [...acc, whatever[curKey]], []); // get array of values
  }

  myLoopable.forEach(value => console.log(value));
}

This is an example, not the best, you must do your own to check if it is object or not to make sure your function not failed