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fix: cache isFireFox() result in CSSParser to avoid repeated UA scan #1706

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fix: cache isFireFox() result in CSSParser to avoid repeated UA scan #1706

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dd445c4
Merge pull request #1700 from jd-opensource/dev
raoenhui Jun 25, 2026
1db9590
fix: cache isFireFox() result in CSSParser to avoid repeated UA scan
498755303 Jul 22, 2026
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8 changes: 6 additions & 2 deletions src/sandbox/scoped_css.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ class CSSParser {
private scopecssDisableSelectors: Array<string> = [] // disable or enable scopecss for specific selectors
private scopecssDisableNextLine = false // use block comments /* scopecss-disable-next-line */ to disable scopecss on a specific line
private optionCssSelectors: Array<string> = [] // use this option to include specific selectors, so that they will be affected by scopecss ,like microApp.options.optionCss
private isFF = false // cache isFireFox() result per exec, avoid repeated UA scan in recordResult

public exec (
cssText: string,
Expand All @@ -46,18 +47,21 @@ class CSSParser {
this.prefix = prefix
this.baseURI = baseURI
this.linkPath = linkPath || ''
// cache isFireFox() once per exec, recordResult runs for every fragment
this.isFF = isFireFox()
// fetch optionCss configure
this.optionCssSelectors = microApp.options.optionCss || []

this.matchRules()
return isFireFox() ? decodeURIComponent(this.result) : this.result
return this.isFF ? decodeURIComponent(this.result) : this.result
}

public reset (): void {
this.cssText = this.prefix = this.baseURI = this.linkPath = this.result = ''
this.scopecssDisable = this.scopecssDisableNextLine = false
this.scopecssDisableSelectors = []
this.optionCssSelectors = []
this.isFF = false
}

// core action for match rules
Expand Down Expand Up @@ -471,7 +475,7 @@ class CSSParser {
// splice string
private recordResult (strFragment: string): void {
// Firefox performance degradation when string contain special characters, see https://github.com/jd-opensource/micro-app/issues/256
if (isFireFox()) {
if (this.isFF) {
this.result += encodeURIComponent(strFragment)
} else {
this.result += strFragment
Expand Down