在对象数组中搜索对象时，是否有返回 true 或 false 的函数？

Question

I'm looking for a good way to check if an object exist in an array of objects. The intended result is true when all keys/values are present in the same object in that array.

The answers I found by browsing stackoverflow like Find object by id in an array of JavaScript objects which is using jQuery.grep or Find a value in an array of objects in Javascript return the found object. What I'm looking for is a boolean result (not the found object).

I know that I can loop for all array elements and then compare each value....etc

But what I mean is if there is a way to use JS methods like this:

 var listOfObjecs = [ {id: 1, name: "Name 1", score: 11}, {id: 2, name: "Name 2", score: 22}, {id: 3, name: "Name 3", score: 33}, {id: 4, name: "Name 4", score: 44}, {id: 5, name: "Name 5", score: 55}, ]; var isObjectExist = function(search){ return listOfObjecs.filter(function(obj){ if(obj.id===search.id && obj.name===search.name && obj.score===search.score){ return true; } return false; }); } console.log( isObjectExist({id: 3, name: "Name 3", score: 33}) ); //outputs the found object [{id: 3, name: "Name 3", score: 33}] console.log( isObjectExist({id: 9, name: "Name 3", score: 33}) ); //outputs an empty object []

This is because:

The filter() method creates a new array with all elements that pass the test implemented by the provided function.

If there is no native JavaScript method (returning true or false) how can update the isObjectExist() function to return true or false?

Answer 1

The Array.prototype.some method:

The some() method checks if any of the elements in an array pass a test (provided as a function). The some() method executes the function once for each element present in the array: If it finds an array element where the function returns a true value, some() returns true (and does not check the remaining values)

Answer 2

I'm sharing an example based on comments above, it may help others:

 const listOfObjecs = [ { id: 1, name: "Name 1", score: 11 }, { id: 3, name: "Name 3", score: 33 }, { id: 2, name: "Name 2", score: 22 }, { id: 3, name: "Name 3", score: 33 }, { id: 4, name: "Name 4", score: 44 }, { id: 5, name: "Name 5", score: 55 }, { id: 3, name: "Name 3", score: 33 }, ]; const search1 = { id: 3, name: "Name 3", score: 33 }; const search2 = { id: 9, name: "Name 3", score: 33 }; // Using Array.prototype.some() const resSomeSearch1 = listOfObjecs.some(item => JSON.stringify(item) === JSON.stringify(search1)); console.log(`resSome(search1): ${resSomeSearch1}`); // outputs: true const resSomeSearch2 = listOfObjecs.some(item => JSON.stringify(item) === JSON.stringify(search2)); console.log(`resSome(search2): ${resSomeSearch2}`); // outputs: false // Using Array.prototype.filter() const resFilterSearch1 = !!listOfObjecs.filter(item => JSON.stringify(item) === JSON.stringify(search1)).length; console.log(`resFilter(search1): ${resFilterSearch1}`); // outputs: true const resFilterSearch2 = !!listOfObjecs.filter(item => JSON.stringify(item) === JSON.stringify(search2)).length; console.log(`resFilter(search2): ${resFilterSearch2}`); // outputs: false // Using Array.prototype.find() const resFindSearch1 = !!listOfObjecs.find(item => JSON.stringify(item) === JSON.stringify(search1)); console.log(`resFind(search1): ${resFindSearch1}`); // outputs: true const resFindSearch2 = !!listOfObjecs.find(item => JSON.stringify(item) === JSON.stringify(search2)); console.log(`resFind(search2): ${resFindSearch2}`); // outputs: false

Answer 3

This works for me:

const findInArray = (myArray, item) => {
 !!myArray.find((el) => el == item)
};

Update, even easier:

 ['cat', 'dog', 'bat'].includes('dog');  

Answer 4

The find() method returns a value of the first element in the array that satisfies the provided testing function. Otherwise undefined is returned. So no boolean result.

@AlaDejbali's comment on his post.

Let's take this array :

var arr = [{
        name: "Ala",
        age: 20,
    },
    {
        name: "Jhon",
        age: 22,
    },
    {
        name: "Melissa",
        age: 12,
    },
];

Of course, find() returns the whole object inside your array but that depends on your implemented function inside find for example :

function findObject(arr, value) {
    if (Array.isArray(arr)) {
        return arr.find((value) => {
            return value.age === 20;
        });
    }
}

When we call this function like this :

console.log(findObject(arr, 20));

The resul will be :

{name: "Ala", age: 20}

And as far as we know undefined is not an object so we can test the returned result :

function findObject(arr, value) {
    const element = arr.find((value) => {
        return value.age === 20;
    });
    return typeof element === "object" ? true : false;
}

Or in other way :

function findObject(arr, value) {
        const element = arr.find((value) => {
            return value.age === 20;
        });
        return typeof element === "undefined" ? false : true;
    }

Answer 5

return boolean value if an object exists in array of objects.

 var listOfObjecs = [ { id: 1, name: "Name 1", score: 11 }, { id: 2, name: "Name 2", score: 22 }, { id: 3, name: "Name 3", score: 33 }, { id: 4, name: "Name 4", score: 44 }, { id: 5, name: "Name 5", score: 55 }, ]; var object = { id: 3, name: "Name 3", score: 33 }; var booleanValue = listOfObjecs.filter((item) => item.id === object.id && item.name === object.name && item.score === object.score).length > 0 console.log({booleanValue})

Answer 6

尝试这个：

!!arr.find(function(){...})