Website Structure

Frontend-Learner/node_modules/koa-compose/index.js

@@ -0,0 +1,48 @@
+'use strict'
+
+/**
+ * Expose compositor.
+ */
+
+module.exports = compose
+
+/**
+ * Compose `middleware` returning
+ * a fully valid middleware comprised
+ * of all those which are passed.
+ *
+ * @param {Array} middleware
+ * @return {Function}
+ * @api public
+ */
+
+function compose (middleware) {
+  if (!Array.isArray(middleware)) throw new TypeError('Middleware stack must be an array!')
+  for (const fn of middleware) {
+    if (typeof fn !== 'function') throw new TypeError('Middleware must be composed of functions!')
+  }
+
+  /**
+   * @param {Object} context
+   * @return {Promise}
+   * @api public
+   */
+
+  return function (context, next) {
+    // last called middleware #
+    let index = -1
+    return dispatch(0)
+    function dispatch (i) {
+      if (i <= index) return Promise.reject(new Error('next() called multiple times'))
+      index = i
+      let fn = middleware[i]
+      if (i === middleware.length) fn = next
+      if (!fn) return Promise.resolve()
+      try {
+        return Promise.resolve(fn(context, dispatch.bind(null, i + 1)));
+      } catch (err) {
+        return Promise.reject(err)
+      }
+    }
+  }
+}