core&ui: add progress callback (beta)

packages/hydrooj/src/handler/problem.ts

@@ -251,6 +251,7 @@ export class ProblemMainHandler extends Handler {
 
     @param('pids', Types.NumericArray)
     async postDelete(domainId: string, pids: number[]) {
+        let i = 0;
         for (const pid of pids) {
             // eslint-disable-next-line no-await-in-loop
             const pdoc = await problem.get(domainId, pid);
@@ -258,6 +259,8 @@ export class ProblemMainHandler extends Handler {
             if (!this.user.own(pdoc, PERM.PERM_EDIT_PROBLEM_SELF)) this.checkPerm(PERM.PERM_EDIT_PROBLEM);
             // eslint-disable-next-line no-await-in-loop
             await problem.del(domainId, pid);
+            i++;
+            this.progress(`Deleting: (${i}/${pids.length})`);
         }
         this.back();
     }