在 function 中返回“typeof”值？

Question

I'm a total beginner, so it would be very helpful if someone posted the full solution in the comments.

I'm trying to solve the following challenge on edabit:

Create a function that takes an array and returns the types of values (data types) in a new array.

arrayValuesTypes([1, 2, "null", []])
// expected output ➞ ["number", "number", "string", "object"]

arrayValuesTypes(["214", true, false, 2, 2.15, [], null])
// expected output ➞ ["string", "boolean", "boolean", "number", "number", "object", "object"]

arrayValuesTypes([21.1, "float", "array", ["I am array"], null, true, 214])
// expected output ➞ ["number", "string", "string", "object", "object", "boolean", "number"]

So far I have this:

    arr = [1, 2, "null", []]
    
    function arrayValuesTypes(arr) {
        for (let i = 0; i < arr.length; i++) {
         return typeof arr[i]
      }
    }

// output ➞
// 'number'

But when I change "return" to a console.log, it gives me a result closer to what I am looking for. Why is that?

arr = [1, 2, "null", []]

function arrayValuesTypes(arr) {
    for (let i = 0; i < arr.length; i++) {
     console.log(typeof arr[i])
  }
}
// output ➞
// 'number'
// 'number'
// 'string'
// 'object'

Answer 1

When you wrote 'return', it will do the loop once and then stop. why? because return stops the action. In this case, it stops the loop. And that's why you got the output of the first item in the array- type number

Answer 2

Why is that?

Because return inside a function will return the value and so stop the function, regardless of the for loop.

---

So use map() to apply it for each item in the array, and then return that array created by map :

 function arrayValuesTypes(arr) { return arr.map(tmp => typeof tmp); } const tests = [ [1, 2, "null", []], ["214", true, false, 2, 2.15, [], null], [21.1, "float", "array", ["I am array"], null, true, 214] ]; for (let testIndex in tests) { console.log(arrayValuesTypes(tests[testIndex])); }

["number", "number", "string", "object"] 
["string", "boolean", "boolean", "number", "number", "object", "object"] 
["number", "string", "string", "object", "object", "boolean", "number"]

Answer 3

This should do the work:

let arr = [1, 2, "null", []]


function arrayValuesTypes(arr) {
    return arr.map(a=>typeof a)
}

Answer 4

Try this:

 arr = [1, 2, "null", []] function arrayTypes(arr) { //Create an empty list to hold values arrayWithTypes = [] //Loop for (var x of arr) { //Push values in the above empty list arrayWithTypes.push(String(typeof(x))) } //Return the final array return arrayWithTypes } console.log(arrayTypes(arr))