feat(scully): Add replaceFirstRouteParamWithVal util (#123)

* feat(scully): Add replaceFirstRouteParamWithVal util

Often people will need to replace the first route param
with a value. To prevent them from recreating the split
logic and join logic and break logic, this function is
a reusable util that people can use.

* run prettier on the code, and export the function so that
others can use it via npm.

Author: aaronfrost

scully/index.ts

@@ -4,6 +4,17 @@ import {HandledRoute} from './routerPlugins/addOptionalRoutesPlugin';
 import {updateScullyConfig} from './utils/config';
 import {RouteTypes, ScullyConfig} from './utils/interfacesandenums';
 import {routeSplit} from './utils/routeSplit';
+import {replaceFirstRouteParamWithVal} from './utils/replaceFirstRouteParamWithVal';
 import {startScully} from './utils/startup';
 
-export {startScully, updateScullyConfig, ScullyConfig, registerPlugin, HandledRoute, RouteTypes, routeSplit, configValidator};
+export {
+  startScully,
+  updateScullyConfig,
+  ScullyConfig,
+  registerPlugin,
+  HandledRoute,
+  RouteTypes,
+  routeSplit,
+  replaceFirstRouteParamWithVal,
+  configValidator,
+};

scully/utils/replaceFirstRouteParamWithVal.ts

@@ -0,0 +1,20 @@
+/**
+ * This function replaces the first instance of a route param with the passed value
+ * @param route - the route from scullyconfig.routes section
+ * @param val - a string that you will be adding into the parameterized route
+ *
+ * replaceFirstRouteParamWithVal('/foo/:bar', '123')        // '/foo/123'
+ * replaceFirstRouteParamWithVal('/foo/:bar/:baz', '123')   // '/foo/123/:baz'
+ */
+export function replaceFirstRouteParamWithVal(route: string, val: string): string {
+  const pieces: string[] = route.split('/');
+  for (let i = 0; i < pieces.length; i++) {
+    if (pieces[i].startsWith(':')) {
+      pieces[i] = val;
+      // Once you replace a param, break the loop.
+      // This allows you to use this on routes with multiple params.
+      break;
+    }
+  }
+  return pieces.join('/');
+}