CODEWITHSUNDEEP
javascript
GLP
GLP

Reputation: 3685

How to get the length of an object after checking it is an array in Javascript

I have an array of objects, there is one field in each object could be boolean or a string of array, for instance

myObjects=[{id: "fruit", selected: true}, {id: "veggie", selected: ["tomato", "cucumber", "potato"]}, {id: "diary", selected:[]}]

I would like to filter out the objects that have selected either not empty or true. The result would be:

result=[{id: "fruit", selected: true}, {id: "veggie", selected: ["tomato", "cucumber", "potato"]}]

Here is my code:

for (const object in myObjects) {
if (!object[selected] || (Array.isArray(object[selected] && object[selected].length ===0)) continue
...
}

But objects with selected is empty array won't get filter out. I got a typescript error

Property 'length' does not exist on type 'boolean | string[]'.
  Property 'length' does not exist on type 'false'.

Can anyone help?

Upvotes: 0

Views: 114

Answers (2)

TAHER El Mehdi
TAHER El Mehdi

Reputation: 9243

You could do it with loop for...of

add object to result array only if selected property is boolean and true:

(typeof object.selected === "boolean" && object.selected)

or selected property is an array and have elements:

(Array.isArray(object["selected"]) && object["selected"].length !== 0)


const myObjects = [{
    id: "fruit",
    selected: true,
  },
  {
    id: "veggie",
    selected: ["tomato", "cucumber", "potato"],
  },
  {
    id: "diary",
    selected: [],
  },
];
let result = [];
//                vv replace 'in' with 'of' since you loop over an array not an object
for (const object of myObjects) {
  if (
    (typeof object.selected === "boolean" && object.selected) ||
    (Array.isArray(object["selected"]) && object["selected"].length !== 0)
  )
    result.push(object);
}
console.log(result);

Upvotes: 0

Sean
Sean

Reputation: 1456

You can use the filter method on the myObjects array

const res = myObjects.filter((object) => object.selected.length > 0 || object.selected === true )

Upvotes: 3

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