console.log('==============================================')
console.log('document.documentElement.clientWidth', document.documentElement.clientWidth)
console.log('document.documentElement.clientHeight', document.documentElement.clientHeight)
console.log('document.documentElement.offsetWidth', document.documentElement.offsetWidth)
console.log('document.documentElement.offsetHeight', document.documentElement.offsetHeight)
console.log('document.documentElement.scrollWidth', document.documentElement.scrollWidth)
console.log('document.documentElement.scrollHeight', document.documentElement.scrollHeight)
console.log('document.documentElement.scrollTop', document.documentElement.scrollTop)
console.log('document.documentElement.scrollLeft', document.documentElement.scrollLeft)
console.log('window.screen.height', window.screen.height)
console.log('window.screen.width', window.screen.width)
console.log('window.screen.availHeight', window.screen.availHeight)
console.log('window.screen.availWidth', window.screen.availWidth)
console.log('window.screenTop', window.screenTop)
console.log('window.screenLeft', window.screenLeft)
有關DTD的問題奕巍。
頁面指定了DTD呵燕，即指定了DOCTYPE時窘面，使用document.documentElement翠语。
頁面沒有DTD，即沒指定DOCTYPE時财边，使用document.body肌括。
總的 scrollHeight= clientHeight + scrollTop
