Function wrapAsyncFunction

browser-polyfill.js:817–856

(name, metadata)

       *       The generated wrapper function.
       */
      const wrapAsyncFunction = (name, metadata) => {
        return function asyncFunctionWrapper(target, ...args) {
          if (args.length < metadata.minArgs) {
            throw new Error(`Expected at least ${metadata.minArgs} ${pluralizeArguments(metadata.minArgs)} for ${name}(), got ${args.length}`);
          }
          if (args.length > metadata.maxArgs) {
            throw new Error(`Expected at most ${metadata.maxArgs} ${pluralizeArguments(metadata.maxArgs)} for ${name}(), got ${args.length}`);
          }
          return new Promise((resolve, reject) => {
            if (metadata.fallbackToNoCallback) {
              // This API method has currently no callback on Chrome, but it return a promise on Firefox,
              // and so the polyfill will try to call it with a callback first, and it will fallback
              // to not passing the callback if the first call fails.
              try {
                target[name](...args, makeCallback({
                  resolve,
                  reject
                }, metadata));
              } catch (cbError) {
                console.warn(`${name} API method doesn't seem to support the callback parameter, ` + "falling back to call it without a callback: ", cbError);
                target[name](...args);

                // Update the API method metadata, so that the next API calls will not try to
                // use the unsupported callback anymore.
                metadata.fallbackToNoCallback = false;
                metadata.noCallback = true;
                resolve();
              }
            } else if (metadata.noCallback) {
              target[name](...args);
              resolve();
            } else {
              target[name](...args, makeCallback({
                resolve,
                reject
              }, metadata));
            }
          });
        };
      };

      /**
       * Wraps an existing method of the target object, so that calls to it are