perf: don't manipulate an empty value

[GalacticHypernova]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

We should not iterate and make O(n) operations on an empty values (strings, arrays), just to receive the same empty value back.

📝 Checklist

• I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.

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[GalacticHypernova]

@danielroe
The failing tests don't really have anything to do with the PR... I haven't changed anything in the component island URL's.

Is this something I accidentally did with one of the changes?

[danielroe]

I don't see an issue with the previous code here...

[GalacticHypernova]

This is kind of the same principle as everything else, if the array is empty the performance overhead to begin checking the iteration (even if exiting immediately) is much bigger than checking for a truthy length. I'll be able to append benchmark results when I get on PC but there was a notable increase in performance.

[GalacticHypernova]

Update: here it is.

const routeRulesMatcher=""
function defu(table, ...args){

}
const prerenderedRoutes=new Set()
const payloadSuffix=""
const nitro={
    _prerenderedRoutes:[]
}
console.time("current")
for (let index = 0; index < 100000; index++) {

    for (const route of nitro._prerenderedRoutes || []) {
        if (!route.error && route.route.endsWith(payloadSuffix)) {
          const url = route.route.slice(0, -payloadSuffix.length) || '/'
          const rules = defu({}, ...routeRulesMatcher.matchAll(url).reverse())
          if (!rules.prerender) {
            prerenderedRoutes.add(url)
          }
        }
    }
}
console.timeEnd("current")
console.time("PR")
for (let index = 0; index < 100000; index++) {
    if (nitro._prerenderedRoutes?.length) {
        for (const route of nitro._prerenderedRoutes) {
          if (!route.error && route.route.endsWith(payloadSuffix)) {
            const url = route.route.slice(0, -payloadSuffix.length) || '/'
            const rules = defu({}, ...routeRulesMatcher.matchAll(url).reverse())
            if (!rules.prerender) {
              prerenderedRoutes.add(url)
            }
          }
        }
    }
}

console.timeEnd("PR")

[danielroe]

Thank you ❤️

[GalacticHypernova]

Always glad to help!