loop over array using charAt to get first letter of each value in javascript

Question

I am new to JS and am trying to understand chartAt. I created a problem where I want to go through an array and pull the first character of each value from my array using charAt. I'm a bit stuck with my code.

var myArray = ['adam', 'bianca', 'cat', 'dennis'];
var myFunc = function (letter) {
    for (var i = 0; i < letter.length; i += 1) {
        letter.charAt(0);
        console.log(letter.charAt(0));
    }
}

Answer 1

In your iteration loop, letter is the array passed to the function myFunc(). You need to access its elements, which you're iterating via i. Use letter[i].charAt(0) instead of letter.charAt(0)

var myArray = ['adam', 'bianca', 'cat', 'dennis'];
var myFunc = function (letter) {
    for (var i = 0; i < letter.length; i += 1) {
        // Use the index i here
        console.log(letter[i].charAt(0));
    }
}

// Call your function, passing in the array you defined:
myFunc(myArray);
// a
// b
// c
// d

So your understanding of String.prototype.charAt() is correct, but the loop iteration was faulty.

Answer 2

If what you want to do is go through each element in the array and get the first letter, you need to iterate over the array, not the word (which you call letter in your solution. So you would have something like this:

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

Or:

myArray.forEach( function(word){
    console.log( word.charAt(0) );
});

Also, you're creating a function (myFunc), but then you're never actually invoking it.

Answer 3

Seems about right, except that you coded a constant in your loop instead of using the loop variable:

var myArray = ['adam', 'bianca', 'cat', 'dennis'];
var myFunc = function (letter) {
    for (var i = 0; i < letter.length; i += 1) {
        letter.charAt(i);
        console.log(letter.charAt(i));
    }
}


> myFunc(myArray[1])
b VM622:6
i VM622:6
a VM622:6
n VM622:6
c VM622:6
a VM622:6
undefined  

You might also want to print out the whole array:

for (var word in myArray) {
    word = myArray[word];
    console.log("");
    myFunc(word);
} 

Answer 4

if you using jQuery

var myArray = ['adam', 'bianca', 'cat', 'dennis'];
$.each(myArray,function(){console.log(this.charAt(0))});

Answer 5

If you are using ES6

const myArray = ['adam', 'bianca', 'cat', 'dennis'];
myArray.forEach(myFunc => console.log(myFunc.charAt(0)));

//output
a
b
c
d

If you want to put the output in an array

const myArray = ['adam', 'bianca', 'cat', 'dennis'];
const myFunc = myArray.map(name => name.charAt(0));  

console.log(myFunc); 
//output
[ 'a', 'b', 'c', 'd' ]

// When .map() is called on an array, it takes an argument of a callback function and returns a new array