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TA貢獻(xiàn)1943條經(jīng)驗(yàn) 獲得超7個(gè)贊
文檔比電腦屏幕還要長(zhǎng)的時(shí)候,瀏覽器就只能看一部分,相當(dāng)于一個(gè)取景框,這個(gè)框到這個(gè)文檔頂端的距離為 scrollTop
a document
^ +-----------+ ^
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offsetTop| | viewport | |
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v | +--+ #js_productWrap
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| +--+ | |
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+-----------------+
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+-----------+
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