arrays-article-code

every-flag.js

function areAllValuesEqualOne (input) {
    var flag = true;

    for (var i = 0; i < input.length; i++) {
        if (input[i] !== 1) flag = false;
    }

    return flag;
}

every.js

function areAllValuesEqualOne (input) {
    return input.every(function (value, i) {
        return value === 1;
    });
}

filter.js

function isEven (number) {
    return number % 2 === 0;
}

[0, 1, 2, 3, 4, 5].filter(isEven); // [0, 2, 4]

function getEveryThirdValue (value, i) {
    return (i + 1) % 3 === 0;
}

[0, 1, 2, 3, 4, 5].filter(getEveryThirdValue); // [2, 5]

flatten.js

function flatten (input) {
    return input.reduce(function (acc, value, i) {
        return acc.concat(Array.isArray(value) ? flatten(value) : value);
    }, []);
}

console.log(flatten([1, 2, [3, 4,[5, 6], 7], 8, 9])); // [1, 2, 3, 4, 5, 6, 7, 8, 9];

for.js

var arr = [0, 1, 2, 3];
for (var i = 0, len = arr.length; i < len; i++) {
    // perform some operation on arr[i];
}

foreach.js

[0, 1, 2, 3].forEach(function (value, i) {
    // perform some operation on a value;
});

longest-word.js

function getMaximumStringLength (list) {
    return list.reduce(function (acc, value) {
        return value.length > acc ? value.length : acc;
    }, 0);
}

map.js

var foo = [0, 1, 2, 3];
var bar = foo.map(function (value, i) {
    return value + 5;
});
console.log(bar); // [5, 6, 7, 8]

movies-rating-curried.js

var getMoviesWithRatingOver2 = function (movies) {
    return getMoviesWithRatingOverN.call(null, movies, 2);
};
var getMoviesWithRatingOver3 = function (movies) {
    return getMoviesWithRatingOverN.call(null, movies, 3);
};
var getMoviesWithRatingOver4 = function (movies) {
    return getMoviesWithRatingOverN.call(null, movies, 4);
};

movies-rating.js

function getMoviesWithRatingOverN (movies, n) {
    return movies.filter(function (movie) {
        return movie.rating > n;
    });
}

var results = getMoviesWithRatingOverN([
    {name: 'a', rating: 2 },
    {name: 'b', rating: 3.5 },
    {name: 'c', rating: 4.1 },
    {name: 'd', rating: 5 },
    {name: 'e', rating: 3.4 }
], 4);

console.log(results); // [{name: 'c', rating: 4.1 }, {name: 'd', rating: 5 }]

reduce.js

[1, 2, 3, 4, 5].reduce(function (acc, value, i) {
    return acc + value;
});
// returns 15, as 1 became starting value

[1, 2, 3, 4, 5].reduce(function (acc, value, i) {
    return acc + value;
}, 10);
// returns 25, as 10 was starting value

[['car', 'Chevrolet'], ['model', 'Camaro'], ['color', 'yellow']].reduce(function (acc, value, i) {
    acc[value[0]] = value[1];
    return acc;
}, { name: 'Bumblebee' });
// other data types can be used as an accumulator as well
// {name: 'Bumblebee', car: 'Chevrolet', model: 'Camaro', color: 'yellow'}

some.js

function doesAnyValueEqualsOne (input) {
    return input.some(function (value, i) {
        return value === 1;
    });
}

utils.js

_.map(myArray, function (value, i) { ... });
_.filter(myArray, function (value, i) { ... });
_.reduce(myArray, function (acc, value, i) { ... });

validation.js

function isFormFilled (form) {
    // get all inputs and selects and merge them into single array. Because querySelectorAll is returning nodeList, which has to be transformed into array to perform any array-based methods on it, we've to use slice method on our query results.
    var slice = Array.prototype.slice; // just a quick shorthand
    var inputs = slice.call(form.querySelectorAll('input')).concat(slice.call(form.querySelectorAll('select')));
    
    return inputs.map(function (input) {
        return input.value;
    }).every(function (value) {
        return value !== '' && value !== '0';
    });
}

votes.js

function getTotalVotesNumber (movies) {
    return movies.map(function (movie) {
        return parseInt(movie.votes, 10);
    }).reduce(function (acc, vote) {
        return acc + vote;
    }, 0);
}