如何检查具有多个对象的数组中的值是否存在-JavaScript？

Question

So my array looks like this:

let array = [
    {"object1":1},
    {"object2":2},
    {"object3":3}
];

What I want to do is to check, for example, whether or not "object1" exists. The way I would prefer is pure Javascript.

I am doing this for large chunks of data and so my code needs to be something like this:

if ("opensprint1" in array){
  console.log("yes, this is in the array");
} else {
  console.log("no, this is not in the array");
};

NOTE: I have tried to use the (in) function in JS and the (hasOwnProperty) and neither has worked.

Any ideas?

Answer 1

if ("opensprint1" in array){

That check for the array keys, so it would work with:

if ("0" in array){

But actually you want to check if some of the array elements got that key:

if(array.some( el => "opensprint1" in el))

Answer 2

You're trying to filter an array of objects. You can pass a custom function into Array.prototype.filter , defining a custom search function. It looks like you want to search based on the existence of keys. If anything is returned, that key exists in the object array.

 let array = [{ "object1": 1 }, { "object2": 2 }, { "object3": 3 } ]; const filterByKey = (arr, keyName) => array.filter(obj => Object.keys(obj).includes(keyName)).length > 0; console.log(filterByKey(array, 'object1')); console.log(filterByKey(array, 'object5')); 

That is roughly equivalent to:

 let array = [{ "object1": 1 }, { "object2": 2 }, { "object3": 3 } ]; const filterByKey = (arr, keyName) => { // iterate each item in the array for (let i = 0; i < arr.length; i++) { const objectKeys = Object.keys(arr[i]); // take the keys of the object for (let j = 0; j < objectKeys.length; j++) { // see if any key matches our expected if(objectKeys[i] === keyName) return true } } // none did return false; } console.log(filterByKey(array, 'object1')); console.log(filterByKey(array, 'object5')); 

Answer 3

This might help you

let array = [
    {"object1":1},
    {"object2":2},
    {"object3":3}
];

let targetkey = "opensprint1";
let exists  = -1;
for(let i = 0; i < array.length; i++) {
    let objKeys = Object.keys(array[i]);
    exists = objKeys.indexOf(targetkey);
    if (exists >= 0) {
        break;
    }
}

if (exists >= 0) {
    console.log("yes, this is in the array");
} else {
   console.log("no, this is not in the array");
}

Answer 4

In this case, I think one of the most efficient way is to do a for and break like:

 let array = [ {"object1":1}, {"object2":2}, {"object3":3} ]; exist = false; for(let i = 0; i<array.length; i++){ if("object1" in array[i]){ exist = true;//<-- We just know the answer we want break;//<-- then stop the loop } } console.log(exist); 

When iteration finds a true case, stops the iteration. We can't perform a break in .map , .filter etc. So the number of iterations are the less possible. I think this is also the case of .some()

Answer 5

let array = [
 { "object1": 1 },
 { "object2": 2 },
 { "object3": 3 }
];

let checkKey = (key) => {
 var found = false;
 array.forEach((obj) => {
     if (!(obj[key] === undefined)) {
         found = true;
         array.length = 0;
     }
 });
 return found;
}
console.log(checkKey("object2"));