jQuery AJAX cache:false and RESTful query parameter validation

Direct Answer

No. jQuery’s cache:false implementation always appends a unique _t query parameter to GET requests. There is no documented option to suppress that parameter while still disabling the browser cache, and jQuery does not provide a native setting that tells the browser to rely solely on HTTP Cache-Control headers instead of timestamp-based cache busting.

Why This Happens

When cache:false is set, jQuery’s internal ajax method generates a cache-busting token by appending _t= to the URL. This behavior is hard‑coded in the library (see jQuery.ajaxPrefilter for jsonp and the cache option handling in jquery/src/ajax.js). The purpose is to force a fresh request by making every URL unique, which works at the browser level but leaks into the query string seen by your API.

Browsers honor Cache‑Control, ETag, and Last‑Modified headers automatically—no client‑side JavaScript is required. jQuery cannot add, remove, or modify those response headers; they are entirely controlled by the server. Setting cache:true (the default) simply lets the browser apply its normal caching logic based on the headers the server sends.

Practical Workarounds

1. Keep cache:true and configure server headers. Send Cache‑Control: max‑age=60, must‑revalidate (or no‑cache if you want revalidation on every request). The browser will cache and revalidate using If‑None‑Match/If‑Modified‑Since automatically.
2. Whitelist the _t parameter on the API side. If you must use cache:false, adjust your validation middleware to ignore unknown query parameters or explicitly allow _t.
3. Implement conditional GET manually. In a beforeSend callback, add If‑Modified‑Since or If‑None‑Match headers based on values you stored from a previous response. This gives you cache‑busting control without a query string, but you must manage the stored validators yourself.
4. Use a different HTTP client. Libraries like axios or the native fetch API let you set cache: 'no-store' (fetch) or omit the query‑string busting entirely while still controlling caching via headers.

Verification Steps

// 1. Confirm timestamp injection
$.ajax({ url: '/api/test', cache: false, success: () => {} });
// Open DevTools Network tab → observe ?_t=1234567890 in request URL

// 2. Confirm default behavior (no timestamp)
$.ajax({ url: '/api/test', cache: true, success: () => {} });
// URL should remain unchanged

// 3. Test server-driven caching
// Server responds with: Cache-Control: max-age=30
// Make two GETs within 30s with cache:true → second request should be served from disk/memory cache (status 200 from cache) or 304 if must-revalidate

One Diagnostic Detail

Does your API currently return Cache‑Control, ETag, or Last‑Modified headers on the endpoints in question? If not, adding those headers is the first step toward eliminating the need for cache:false altogether.