array.forEach之后的回调函数

Question

I have a function that compares an array of 2 strings ... eg ['snookums', 'snook'] , which looks to return true if all of the letters in the 2nd string appear in the first, so in this instance, it should return true.

I have it working with a for loop:

function mutation(arr) {
    for (var i = 0; i < arr[1].length; i++) {
        if (arr[0].indexOf(arr[1][i]) === -1) {
            return false;
        }
    }
    return true;
    });
}

However, I would like to get this working in a better way, ultimately with forEach. I have it console logging out false if it comes across a letter which doesn't match, but I am wondering will this work, how will I return true if it gets to the end of the forEach and indexOf() returns true for each letter.

function mutation(arr) {
return arr.pop()
    .split('')
    .forEach(function(letter) {
        console.log(arr[0].indexOf(letter) === -1);
    });
}
console.log(mutation(["snookums", "for"]));

Does that make sense?

Thank you

Answer 1

forEach is not a "better" way. What you are looking for is the every method :

function mutation(arr) {
    return arr[1].split("").every(function(letter) {
        return arr[0].indexOf(letter) !== -1;
    });
}