CODEWITHSUNDEEP
javascriptarrays
Melo
Melo

Reputation: 71

Creating objects with constructor inside array literal

I'm trying to create a object using my constructor Person, but it doesn't work when I initialize the object directly in the array that uses literal notation.

function Person (name, age) {
    this.name = name;
    this.age = age;
} 

var family = [
    [ new Person("alice", 40)   ],
    [ new Person("bob", 42)     ],
    [ new Person("michelle", 8) ],
    [ new Person("timmy", 6)    ]
];

for (var person in family) {
    console.log(family[person].name);
}

But it just prints undefined four times.

I gotta use this notation:

var family = new Array();
family[0] = new Person("alice", 40);
family[1] = new Person("bob", 42);
family[2] = new Person("michelle", 8);
family[3] = new Person("timmy", 6);

So it prints alice, bob, michelle, timmy.

What am I doing wrong?

Upvotes: 1

Views: 1263

Answers (2)

Christos
Christos

Reputation: 53958

You could just use this:

var family = [
     new Person("alice", 40),
     new Person("bob", 42),
     new Person("michelle", 8),
     new Person("timmy", 6)    
];

There isn't any need of enclosing each Person in brackets.

Now you can loop through the items of your array like below:

for (var index=0; index<family.length; index++) {
    console.log(family[index].name);
}

I didn't use the for..in since this exists for another reason:

The for..in statement iterates over the enumerable properties of an object, in arbitrary order. For each distinct property, statements can be executed.

For more detais about for...in, please have a look here.

function Person (name, age) {
    this.name = name;
    this.age = age;
} 

var family = [
         new Person("alice", 40),
         new Person("bob", 42),
         new Person("michelle", 8),
         new Person("timmy", 6)    
    ];

for (var index=0; index<family.length; index++) {
    document.write(family[index].name);
    document.write("</br>");
}

Upvotes: 2

tymeJV
tymeJV

Reputation: 104775

You're actually creating a 2D array - I think you only want a regular array, then use a regular for loop to iterate:

var family = [
    new Person("alice", 40), //omit the inner arrays, etc./.
];

for (var i = 0; i < family.length; i++) { 
    //check em out
    console.log(family[i].name);
}

Upvotes: 1

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