nonsense.js

const MAX_LENGHT_FILE = 7;
const MAX_UPLOAD_SIZE = 5000000;
const temporaryFileList = [];

const dangerToast = (text) => {
    console.error(text);
};

const maxLenghtFilesIsValid = (files = []) => {
    if (!Array.isArray(files)) {
        throw Error('only array')
    }
    return files.length <= MAX_LENGHT_FILE;
}

const getFileSize = (files) => {
    /**
     * ... code
     */
    return 0;
}

const getDropSize = (files) => {
    /**
     * code
     */
    return 0;
}


const fillTemporaryArray = (files) => {

    if (!maxLenghtFilesIsValid(files)) {
        dangerToast('Limite atingido');
        return;
    }

    if ((getDropSize(files) + getFileSize(files)) >= MAX_UPLOAD_SIZE ) { //just a joke
        dangerToast('Limite de tamanho')
        return;
    }

    files.forEach(el => {
        temporaryFileList.push(el);
    });
}


const f = ['foo', 'bar'];

fillTemporaryArray(f);