如果在“for in”循环中

Question

Checking for equality of two objects:

I am not sure about how my code flows and how can I fix this.

Inside areEqual function, I am checking "value" of two objects.

if they are equal -> isEqual=true -> for loop shall continue if one of values are not equal -> isEqual = false and Break from the loop.

But i don't get the desired results. What logic am i exactly not understanding here?

    function Address (street, city, zipCode) {
    this.street = street; 
    this.city = city; 
    this.zipCode = zipCode; 
}

let address1 = new Address('a', 'b', 'c'); 
let address2 = new Address('a', 'd', 'c'); 


//checking for equality between two objects
function areEqual(address1, address2){  
    let isEqual = true; 
        for(let key in address1) {
            if(address1[key] === address2[key])
                isEqual = true; 
            else
                isEqual = false
                break; 
        }
    if(isEqual) return 'They are equal'; 
        else return 'They are not equal'; 

}

console.log(areEqual(address1, address2)); 

Answer 1

Your code is equivalent to:

if (address1[key] === address2[key])
  isEqual = true;
else 
  isEqual = false

break;

You need to wrap your else condition in {} . Currently it breaks out of the loop on the first iteration

 function Address(street, city, zipCode) { this.street = street; this.city = city; this.zipCode = zipCode; } let address1 = new Address('a', 'b', 'c'); let address2 = new Address('a', 'd', 'c'); let address3 = new Address('x', 'y', 'z'); let address4 = new Address('x', 'y', 'z'); //checking for equality between two objects function areEqual(address1, address2) { let isEqual = true; for (let key in address1) { if (address1[key] === address2[key]) isEqual = true; else { isEqual = false break; } } if (isEqual) return 'They are equal'; else return 'They are not equal'; } console.log(areEqual(address1, address2)); console.log(areEqual(address3, address4));

You can avoid these type of errors if you format your code. Every code editor will have a shortcut for this functionality.

Note : Since you have constructor function for Address , this code will work. But note that, this just checks if the keys in address1 have the same value as address2 . If you compare an empty object like this areEqual({}, address2) it will log They are equal because it never enters the for loop. So, you can add an additional check if Object.keys(address1).length is same as that of address2

Answer 2

You have default value of isEquls: true, so if any of keys pair will be not equals than set isEquls to false and break the loop:

function Address (street, city, zipCode) {
    this.street = street; 
    this.city = city; 
    this.zipCode = zipCode; 
}

let address1 = new Address('a', 'd', 'd'); 
let address2 = new Address('a', 'd', 'c'); 


//checking for equality between two objects
function areEqual(address1, address2){  
    let isEqual = true; 
        for(let key in address1) {
            if(address1[key] !== address2[key])
            {
                isEqual = false
                break; 
            }
        }
    if(isEqual) return 'They are equal'; 
        else return 'They are not equal'; 

}

console.log(areEqual(address1, address2));