Overview
Pages often need to wait for AJAX before navigating, chaining requests, or re-enabling buttons. jQuery deferreds represent in-flight HTTP calls.
Blocking the browser with async:false is deprecated—use promises instead.
Implementation
Return $.ajax(...) and chain .then(). Combine multiple calls with $.when(req1, req2).done(...). Disable submit until .always() re-enables.
For ordered steps, nest then or use async functions with await fetch.
When implementing guidance from Waiting for AJAX response, start in a controlled environment that mirrors production versions of operating systems, runtimes, and network policies. Capture a baseline before changes: export configs, snapshot VMs, or tag releases in source control so rollback stays straightforward if behavior regresses.
Document prerequisites, expected outcomes, and verification steps in a short runbook. Automated checks—smoke tests, health endpoints, or query validations—catch regressions early when platforms receive patches. Security belongs in every workflow: apply least privilege, rotate secrets, and review audit logs after deployment.
If results differ across machines, compare environment variables, permission models, time zones, and regional settings. Intermittent issues often trace to caching layers, stale DNS, or duplicated services bound to the same port.
Example
const save = $.post('/api/save', data);
save.done(result => console.log('saved', result));
save.fail(() => alert('Save failed'));
save.always(() => $('#btn').prop('disabled', false));Tips
- Show spinners during wait states.
- Handle timeout with $.ajax timeout option.
- Race conditions if user double-clicks—debounce.
- Prefer fetch + await in new code.
- Re-verify after reboots, certificate renewals, or failover exercises.
- Align monitoring and alerts with the failure modes described in this guide.
- Keep vendor documentation links handy for breaking changes between versions.
- Pair automation with a manual spot check during initial production rollout.