How to choose between `window.URL.createObjectURL()` and `window.webkitURL.createObjectURL()` based on browser

Question

From the Firefox developer website, I know that Firefox uses

objectURL = window.URL.createObjectURL(file);

to get url of file type, but in

Answer 1

if (window.URL !== undefined) {
    window.URL.createObjectURL();
} else if (window.webkitURL !== undefined) {
    window.webkitURL.createObjectURL();
} else {
    console.log('Method Unavailable: createObjectURL');
}

Is round-about what you're looking for. Also, THIS example uses the much simpler...

window.URL = window.URL || window.webkitURL;