Looping through an array of objects and running methods in JS OOP

[marcosdipaolo]

I’m learning Javascript OOP here (not ES6) and i have a question to this great community:

At the end of this code you have a for loop generating some click listeners and i found myself lost, since allCars[i] doesn’t work Uncaught TypeError: Cannot read property 'start' of undefined and if I replace the i variable for a harcoded index like 0 it works, and I don’t understand why.
Codepen here: https://codepen.io/marcosdipaolo/pen/oyjQBN .

Thanks a lot.

var allCars = [];
var count = 0;

var Auto = function (brand, year) {
    this.brand = brand;
    this.year = year;
    this.divsId = this.brand + this.year + '_' + count;

    /* start method */
    this.start = function () {
        window.alert('I am a ' + this.brand + ' built in ' + this.year + ' and I am starting');

    } /* /start mehod */

    $('.container.autos')
        .append('<div class="auto" id="' +
            this.divsId + '" data-brand="' +
            this.brand + '" data-year="' +
            this.year + '"><h6>I am a ' +
            this.brand + ' built in ' +
            this.year + '</h6></div>');
    allCars.push(this);
    count++;

}
/* starter objects */
var ford84 = new Auto('ford', 1984);
var peugeot95 = new Auto('Peugeot', 1995);

/* button click event */
$('#button').on('click', function () {
    var newBrand = $('#brand').val();
    var newYear = $('#year').val();
    if (newBrand && newYear) {
        var newAuto = new Auto(newBrand, newYear);
    }
});
/* Cars click events */
var divs = $('.auto');
for (var i = 0; i < allCars.length; i++) {
    $(divs[i]).on('click', function () {
        allCars[i].start();
    });
}

[Paul_Wilkins]

If after the code has run you try allCars[i] then it won’t work, because the for loop has already advanced the i variable to a value that cannot be indexed in the array.

[mawburn]

Mutating a global variable from within a class is not good practice. All your variables should live inside your class and the class should not know about anything other than itself and what it inherits from.