Function wrapObject

browser-polyfill.js:909–994

(target, wrappers = {}, metadata = {})

       * @returns {Proxy<object>}
       */
      const wrapObject = (target, wrappers = {}, metadata = {}) => {
        let cache = Object.create(null);
        let handlers = {
          has(proxyTarget, prop) {
            return prop in target || prop in cache;
          },
          get(proxyTarget, prop, receiver) {
            if (prop in cache) {
              return cache[prop];
            }
            if (!(prop in target)) {
              return undefined;
            }
            let value = target[prop];
            if (typeof value === "function") {
              // This is a method on the underlying object. Check if we need to do
              // any wrapping.

              if (typeof wrappers[prop] === "function") {
                // We have a special-case wrapper for this method.
                value = wrapMethod(target, target[prop], wrappers[prop]);
              } else if (hasOwnProperty(metadata, prop)) {
                // This is an async method that we have metadata for. Create a
                // Promise wrapper for it.
                let wrapper = wrapAsyncFunction(prop, metadata[prop]);
                value = wrapMethod(target, target[prop], wrapper);
              } else {
                // This is a method that we don't know or care about. Return the
                // original method, bound to the underlying object.
                value = value.bind(target);
              }
            } else if (typeof value === "object" && value !== null && (hasOwnProperty(wrappers, prop) || hasOwnProperty(metadata, prop))) {
              // This is an object that we need to do some wrapping for the children
              // of. Create a sub-object wrapper for it with the appropriate child
              // metadata.
              value = wrapObject(value, wrappers[prop], metadata[prop]);
            } else if (hasOwnProperty(metadata, "*")) {
              // Wrap all properties in * namespace.
              value = wrapObject(value, wrappers[prop], metadata["*"]);
            } else {
              // We don't need to do any wrapping for this property,
              // so just forward all access to the underlying object.
              Object.defineProperty(cache, prop, {
                configurable: true,
                enumerable: true,
                get() {
                  return target[prop];
                },
                set(value) {
                  target[prop] = value;
                }
              });
              return value;
            }
            cache[prop] = value;
            return value;
          },
          set(proxyTarget, prop, value, receiver) {