javascript storing for loop result

Question

Is there a way to store the result of the 'for loop' in a variable?

I want to display the two name kevin and elsa in a div for example.

I know i can do john.friends[0].nom, john.friends[1].nom;

but if John has many friends, it will be difficult...

Now the variable friendName gives me just name, I understand why but can't see the solution...

Thanks !

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

};

var john = new Person('john', 28, [new Person('elsa', 29, []), new Person('kevin', 31, [])]);

for (var i = 0; i < john.friends.length; i++) {
    var friendName = john.friends[i].name;
}

alert(friendName);

Solution 1

var friendNames = []; // store their names within a local array

for(var i = 0; i < john.friends.length; i++){
    friendNames.push(john.friends[i].name);
}

console.log(friendNames); // log to the browser (readability) instead of alert

Solution 2

var friendNames = []; // create array to hold friend names

for(var i=0; i < john.friends.length; i++){    
    friendNames.push(john.friends[i].name); // add friend's name to the array
}

console.log(friendNames); // an array containing all of John's friends' names.

Solution 3

You probably want an array of names (list of all the names). Declare friendName = new Array() and friendName.push(john.friends[i].name);

var friendName = new Array();
for (var i = 0; i < john.friends.length; i++) {
    friendName.push(john.friends[i].name);
    //or friendName[i] = john.friends[i].name;
}
//friendName is now an array of names. Use it as you need (the last line is useful for debugging)
for (i = 0; i < friendName.length; i++) alert(friendName[i]);

---

The problem with your old code was that each iteration of the loop would reassign friendName. When i = 0, 'elsa' was assigned to friendName. When i = 1, 'kevin' was reassigned to friendName.

Furthermore, javascript does not have block scoping; it would be like calling var friendName = 'elsa'; var friendName = 'kevin';. Won't crap out the javascript engine, but just watch out for that. Better to declare friendName as an array above the loop as others and I have mentioned.

Solution 4

Since your friends variable is an array, you can just use some of the methods available to you on that type:

var friendString = john.friends.map(function(f) { return f.name; }).join(' ');

In the above example, the map method maps the friends to just their names and then the join method will produce a space separated string of all johns friends.

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