Cad is progressive enhancement?

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**Progressive enhancement** is a strategy of building from a solid, functional **baseline** (semantic HTML that works everywhere) and then *layering on* CSS for presentation and JavaScript for richer behavior — so the core experience works even if the upper layers fail. ## The three layers ```text 1. HTML → content + functionality (works with no CSS/JS) 2. CSS → presentation/layout (enhances appearance) 3. JS → interactivity (enhances behavior) ``` ## A concrete example: a form ```html ``` ```js // Layer 3: IF JS is available, enhance it into a live AJAX search form.addEventListener("submit", (e) => { e.preventDefault(); // upgrade to fetch — no reload fetchResults(form.q.value); }); ``` If JavaScript fails to load (flaky network, error, blocked), the form **still works** via the native submit — the user can still search. JS only *enhances* it. ## Progressive enhancement vs graceful degradation - **Progressive enhancement** — start with the baseline, build *up*. (Bottom-up.) - **Graceful degradation** — start with the full-featured version, ensure it *degrades* acceptably. (Top-down.) Progressive enhancement is generally more robust because the foundation is guaranteed to work. ## Cén fáth a bhfuil sé tábhachtach Táirgeann sé suíomhanna leaisteach, inrochtana agus feidhmíocha: tá an t-ábhar san HTML (maith do SEO, léitheoirí scáileáin agus gréasáin throma/shean-úsáideach), tá an leathanach in-úsáidte roimh/gan JS (ualaigh braisteoireachta níos tapúla, oibríonn sé má bhíonn script lochtach), agus is bónas atá san bhfeabhsúcháin seachas riachtanas. I ndomhain ghréasáin, gréasáin agus theipeanna éagsúla, a bhith ag tógáil ar bhunús HTML oibritheoireachta — in ionad a thuslacadh go fíor i gcónaí JS — cuireann sé suíomh in-úsáidte do gach duine. Ma léirithe na frameworks nua-aimseartha é seo le socrúchán taobh an tsraidh agus "na hard-bhóthar ag feidhmiú ar dtús, uisce a bhreisithe.