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cache compiled eval tags in safeEval feature for better hx-live perf #3888

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Merged
1cg merged 1 commit into from
Jul 13, 2026
+18 −9
Merged

cache compiled eval tags in safeEval feature for better hx-live perf #3888

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27 changes: 18 additions & 9 deletions src/ext/hx-csp.js
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,10 @@
let counter = 0;
let NativeFunction = Function;
let NativeAsyncFunction = Object.getPrototypeOf(async function(){}).constructor;
// Cache compiled script-injected functions by "keys|body" so each unique
// expression is only injected once — critical for hx-live which re-evaluates
// the same expressions on every DOM/input tick.
let safeEvalCache = new Map();

function makeGatedConstructor(isAsync) {
return function(...keys) {
Expand All @@ -136,15 +140,20 @@
return;
}
if (htmx.config.safeEval) {
let fn = `__htmx_eval_${++counter}`;
let script = document.createElement('script');
script.nonce = pageNonce;
script.textContent = ttPolicy.createScript(`window.${fn} = ${isAsync ? 'async ' : ''}function(${keys.join(',')}) { ${body} }`);
document.head.appendChild(script);
script.remove();
let r = window[fn].call(thisArg, ...values);
delete window[fn];
return r;
let cacheKey = keys.join(',') + '|' + body;
let compiled = safeEvalCache.get(cacheKey);
if (!compiled) {
let fn = `__htmx_eval_${++counter}`;
let script = document.createElement('script');
script.nonce = pageNonce;
script.textContent = ttPolicy.createScript(`window.${fn} = ${isAsync ? 'async ' : ''}function(${keys.join(',')}) { ${body} }`);
document.head.appendChild(script);
script.remove();
compiled = window[fn];
delete window[fn];
safeEvalCache.set(cacheKey, compiled);
}
return compiled.call(thisArg, ...values);
}
let Ctor = isAsync ? NativeAsyncFunction : NativeFunction;
return new Ctor(...keys, body).call(thisArg, ...values);
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