How to determine if Javascript array contains an object with an attribute that equals a given value?

Question

I have an array like

vendors = [{
    Name: \'Magenic\',
    ID: \'ABC\'
  },
  {
    Name: \'Microsoft\',
    ID: \'DEF\'
  } // and so on... 
];
         


        

Answer 1

To compare one object to another, I combine a for in loop (used to loop through objects) and some(). You do not have to worry about an array going out of bounds etc, so that saves some code. Documentation on .some can be found here

var productList = [{id: 'text3'}, {id: 'text2'}, {id: 'text4', product: 'Shampoo'}]; // Example of selected products
var theDatabaseList = [{id: 'text1'}, {id: 'text2'},{id: 'text3'},{id:'text4', product: 'shampoo'}];    
var  objectsFound = [];

for(let objectNumber in productList){
    var currentId = productList[objectNumber].id;   
    if (theDatabaseList.some(obj => obj.id === currentId)) {
        // Do what you need to do with the matching value here
        objectsFound.push(currentId);
    }
}
console.log(objectsFound);

An alternative way I compare one object to another is to use a nested for loop with Object.keys().length to get the amount of objects in the array. Code below:

var productList = [{id: 'text3'}, {id: 'text2'}, {id: 'text4', product: 'Shampoo'}]; // Example of selected products
var theDatabaseList = [{id: 'text1'}, {id: 'text2'},{id: 'text3'},{id:'text4', product: 'shampoo'}];    
var objectsFound = [];

for(var i = 0; i < Object.keys(productList).length; i++){
        for(var j = 0; j < Object.keys(theDatabaseList).length; j++){
        if(productList[i].id === theDatabaseList[j].id){
            objectsFound.push(productList[i].id);
        }       
    }
}
console.log(objectsFound);

To answer your exact question, if are just searching for a value in an object, you can use a single for in loop.

var vendors = [
    {
      Name: 'Magenic',
      ID: 'ABC'
     },
    {
      Name: 'Microsoft',
      ID: 'DEF'
    } 
];

for(var ojectNumbers in vendors){
    if(vendors[ojectNumbers].Name === 'Magenic'){
        console.log('object contains Magenic');
    }
}