Error in constructor or array or the for loop?

Question

Here is the code:

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

// Now we can make an array of peoples
var family = new Array();
family[0] = Person("alice", 40);
family[1] = Person("bob", 42);
family[2] = Person("michelle", 8);
family[3] = Person("timmy", 6);

// loop through our new array
for ( i=0; i < family.length; i++; ) {
    console.log(family[i].name)
};

The expected output of this script is:

alice
bob
michelle
timmy

But the output is:

Uncaught TypeError: Cannot read property 'name' of undefined (anonymous function)

Cerbrus · Accepted Answer · 2013-01-03 09:04:31Z

2

Add a new keyword for each Person added, and remove the extra ; in the for-loop (after the i++)

// Now we can make an array of people
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);

// loop through our new array
for ( i=0; i < family.length; i++ ) {
    console.log(family[i].name);       // Also, added a semicolon here. Not required, but it's good practice to close your lines.
};

This will now log:

alice
bob
michelle
timmy

answered Jan 3, 2013 at 9:04

Cerbrus

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Comments

user160820 · Accepted Answer · 2013-01-03 09:05:15Z

0

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

// Now we can make an array of people
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);

console.info(family);
// loop through our new array
for ( i=0; i < family.length; i++ ) {
    console.log(family[i].name)
};

answered Jan 3, 2013 at 9:05

user160820

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1 Comment

JJJ Over a year ago

This is correct, but you should add some comments about what you changed and why.

user1966874 · Accepted Answer · 2013-01-10 13:31:59Z

0

I did something like this:

// Our Person constructor
var Person = function(name,age) {
    this.age = age;
    this.name = name;
};

// Now we can make an array of people
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);

// loop through our new array
for (var famloop in family) {
    console.log(family[famloop].name);
}

answered Jan 10, 2013 at 13:31

user1966874

1

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