样式Javascript下拉菜单

我有一个工作Javascript下拉，从Json文件拉。它工作得很好。

我正试图找出如何样式我的按钮，并使用Twitter Bootstrap 3的特点。我知道Bootstrap 3，我只是对如何访问我的javascript组件来设置它们的样式感到困惑。

这个html调用我的index.html文档中的代码

<div id='form-wrapper'></div>

这里是决定下拉菜单功能的Javascript/Json。

// The JSON this is all pulled from
var json = {
    "Apple": {
        "A / C": {
            "weight": 6,
            "price": 3.99
        },
        "B": {
            "weight": 7,
            "price": 4.99
        }
    },
    "Orange": {
        "1": {
            "weight": 4,
            "price": 4.49
        },
        "2": {
            "weight": 5,
            "price": 5.49
        }
    }
};
// Correct JSON data
for (var a in json) {
    for (var attr in json[a]) {
        if (/'//.test(attr)) {
            var attrs = attr.split(/'s*'/'s*/);
            for (var x = 0, y = attrs.length; x < y; ++ x) {
                json[a][attrs[x]] = json[a][attr];
            }
            json[a][attr] = null;
        }
    }
}
var form_wrapper = document.getElementById("form-wrapper");
// Create the first dropdown
var dropdown1 = document.createElement("select");
// Populate the first dropdown
var option = document.createElement("option");
option.innerHTML = "Select a fruit";
option.value = "none";
dropdown1.appendChild(option);
// Add options from JSON
for (var attr in json) {
    var option = document.createElement("option");
    option.innerHTML = option.value = attr;
    dropdown1.appendChild(option);
}
// Create the second dropdown
var dropdown2 = document.createElement("select");
var option = document.createElement("option");
option.innerHTML = "N/A";
dropdown2.appendChild(option);
// Add weight field
var weight = document.createElement("div");
// Add price field
var price = document.createElement("div");
// Function to automatically fill the weight/price fields
var auto_fill_fields = function() {
    if (dropdown1.value != "none") {
        var obj = json[dropdown1.value][dropdown2.value];
        var weight_str = "Weight: " + obj.weight + " oz";
        var price_str = "Price: $" + obj.price;
    } else {
        var weight_str = "Weight: N/A";
        var price_str = "Price: N/A";
    }
    weight.innerHTML = weight_str;
    price.innerHTML = price_str;
};
// Handle changing the first dropdown
dropdown1.addEventListener("change", function() {
    // Remove the current options from the second dropdown
    $(dropdown2).empty();
    // Did they actually select a fruit?
    if (this.value != "none") { // Yes
        // Populate the second dropdown
        var names = [];
        for (var attr in json[this.value]) {
            if (json[this.value][attr] == null) {
                continue;
            }
            names.push(attr);            
        }
        console.log(names);
        names = names.sort();
        console.log(names);
        for (var x = 0, y = names.length; x < y; ++ x) {
            var option = document.createElement("option");
            option.innerHTML = option.value = names[x];
            dropdown2.appendChild(option);
        }
    } else { // No
        // There's nothing to choose
        var option = document.createElement("option");
        option.innerHTML = "N/A";
        dropdown2.appendChild(option);
    }
    auto_fill_fields();
});
// Handle changing the second dropdown
dropdown2.addEventListener("change", auto_fill_fields);
// Fill in initial values
auto_fill_fields();
// Add submit button
var submit = document.createElement("button");
submit.innerHTML = "submit";
submit.addEventListener("click", function() {
    if (dropdown1.value == "none") {
        return;
    }
    var obj = json[dropdown1.value][dropdown2.value];
    var weight_str = "Weight: " + obj.weight + " oz";
    var price_str = "Price: $" + obj.price;
    var request_str = dropdown1.value + " " + dropdown2.value + " - " + weight_str + ", " + price_str;
    console.log(request_str);
    $.ajax({
        url: "SOMEPLACE",
        data: {
            "key": request_str
        }
    });
});
window.addEventListener("load", function() {
    // Add the first dropdown to the page (body)
form_wrapper.appendChild(dropdown1);
    // Add the second dropdown to the page (body)
    form_wrapper.appendChild(dropdown2);
    // And the rest
    form_wrapper.appendChild(weight);
    form_wrapper.appendChild(price);
    form_wrapper.appendChild(submit);
});