How to choose a weighted random array element in Javascript?

For example: There are four items in an array. I want to get one randomly, like this:

array items = [
    "bike"    //40% chance to select
    "car"     //30% chance to select
    "boat"    //15% chance to select
    "train"   //10% chance to select
    "plane"   //5%  chance to select
]

Sure you can. Here's a simple code to do it:

    // Object or Array. Which every you prefer.
var item = {
    bike:40, // Weighted Probability
    care:30, // Weighted Probability
    boat:15, // Weighted Probability
    train:10, // Weighted Probability
    plane:5 // Weighted Probability
    // The number is not really percentage. You could put whatever number you want.
    // Any number less than 1 will never occur
};

function get(input) {
    var array = []; // Just Checking...
    for(var item in input) {
        if ( input.hasOwnProperty(item) ) { // Safety
            for( var i=0; i<input[item]; i++ ) {
                array.push(item);
            }
        }
    }
    // Probability Fun
    return array[Math.floor(Math.random() * array.length)];
}

console.log(get(item)); // See Console.