dist/jquery.lazyloadxt.extra.js
function getOrDef(obj, prop) {
        return obj[prop] === undefined ? options[prop] : obj[prop];
    }
function getOrDef(obj, prop) {
        return obj[prop] === undefined ? options[prop] : obj[prop];
    }
Return options.prop if obj.prop is undefined, otherwise return obj.prop
@param {*} obj
@param {*} prop
@returns *