Suppose that I have an array in no particular order, and I want to get all values of a given type from that array (for this example, let's use strings).

oldArray = [1, "2", {3: 4}, 5, "6", /7/];
/* ... */
newArray = ["2", "6"];

Logically, I would do something like this:

newArray = [];
oldArray.forEach((element) => {
  if (typeof element === "string") {
    newArray.push(element);
  }
});

(Though it isn't as elegant as the Python one-liner [value for value in oldArray if type(value) == str], it still suffices for me.)

My question is: Is there a more efficient way to do this, or is this an optimal solution?

Suppose that I have an array in no particular order, and I want to get all values of a given type from that array (for this example, let's use strings).

oldArray = [1, "2", {3: 4}, 5, "6", /7/];
/* ... */
newArray = ["2", "6"];

Logically, I would do something like this:

newArray = [];
oldArray.forEach((element) => {
  if (typeof element === "string") {
    newArray.push(element);
  }
});

(Though it isn't as elegant as the Python one-liner [value for value in oldArray if type(value) == str], it still suffices for me.)

My question is: Is there a more efficient way to do this, or is this an optimal solution?

• javascript
• arrays
• sorting
• types

2 Answers 2

Using Array#filter and typeof:

const oldArray = [1, "2", {3: 4}, 5, "6", /7/];

const newArray = oldArray.filter(e => typeof e === 'string');

console.log(newArray);

You can use array.filter():

newArray = oldArray.filter(e => typeof e == "string")