JavaScript代码在输出中打印多余的行（未定义）

Question

need help with this code. What am I doing wrong?

Problem: Create 10 cars, where each car has a color and number. The cars should be numbered in order from 0 to 9. The cars from 0 to 4 should be colored "green" and the cars from 5 to 9 should be colored "blue". Place the cars in order in an array called carGarage.

Guideline: To avoid duplicate code when creating 10 separate cars, first first create a constructor function Car that takes color and number parameters and sets them to this.color and this.number. Then create 10 cars and place them in a carGarage array.

// create a car constructor function
var Car = function(color, number) {
    this.color = color;
    this.number = number;
}
// create a carGarage array
var carGarage = [10];
// create a loop that creates cars and places them in carGarage
for (var i = 0; i <= 9; i++) {
    var color, number;
    i <= 4? color = 'green': color = 'blue';
    number = i;
    var newCar = new Car(color, number);
    carGarage.push(newCar);

}
// test code
for (var i = 0; i < carGarage.length; i++) {
   car = carGarage[i];
   console.log(car.color + " car #" + car.number);
}

Expected Output

green car #0
green car #1
green car #2
green car #3
green car #4
blue car #5
blue car #6
blue car #7
blue car #8
blue car #9

Actual Output

undefined car #undefined
green car #0
green car #1
green car #2
green car #3
green car #4
blue car #5
blue car #6
blue car #7
blue car #8
blue car #9

Answer 1

This line is the key:

var carGarage = [10];

You've initialized array with one element - 10 , not array of length 10. You have to change it to:

var carGarage = [];

So you initialize empty array.

You had 2 times undefined because both 10.color and 10.number aren't defined.