Constructing items within an array literal using a constructor method

Question

Constructing items within an array literal using a constructor method

I am attempting to create an object using my Person constructor. However, I am encountering issues when I try to initialize the object directly in the array using 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);
}

Unfortunately, it only displays undefined four times.

To resolve this issue, I must utilize the following 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);

Upon doing so, I successfully print out alice, bob, michelle, and timmy.

Can someone please point out what mistake I am making?

javascript arrays

Answer 1

Answer №1

You can quickly set up your array of family members like this:

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

No need to wrap each FamilyMember in brackets.

Now you can easily iterate through the array elements with a loop like this:

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

I opted not to use for..in as it serves a different purpose:

The for..in statement loops over an object's enumerable properties in arbitrary order. You can execute statements for each property.

For more information on for...in, check out this link.

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

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

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

Answer 2

You can quickly set up your array of family members like this:

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

No need to wrap each FamilyMember in brackets.

Now you can easily iterate through the array elements with a loop like this:

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

I opted not to use for..in as it serves a different purpose:

The for..in statement loops over an object's enumerable properties in arbitrary order. You can execute statements for each property.

For more information on for...in, check out this link.

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

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

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

Answer 3

Answer №2

Instead of creating a 2D array, it seems like you just need a regular array. To achieve this, simply use a standard for loop for iteration:

var friends = [
    new Person("bob", 35), //avoid using inner arrays
];

for (var j = 0; j < friends.length; j++) { 
    //display names
    console.log(friends[j].name);
}

Answer 4

Instead of creating a 2D array, it seems like you just need a regular array. To achieve this, simply use a standard for loop for iteration:

var friends = [
    new Person("bob", 35), //avoid using inner arrays
];

for (var j = 0; j < friends.length; j++) { 
    //display names
    console.log(friends[j].name);
}

Constructing items within an array literal using a constructor method

Answer №1

Answer №2

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