// 計(jì)算圖片寬高并且定位圖片位置并且圖片的寬高和定位不能超過父元素的大小
functionposition(el,img) {
varimgwidth=img.width
varimgheight=img.height
varparent=el.parentNode
varparentwidth=parent.clientWidth||parent.offsetWidth
varparentheight=parent.clientHeight||parent.offsetHeight
if(imgwidth<=parentwidth) {
if(imgheight>=parentheight) {
imgwidth=imgwidth/ (imgheight/parentheight)
imgheight=parentheight
}
}else{
if(imgheight/ (imgwidth/parentwidth) <=parentheight) {
imgheight=imgheight/ (imgwidth/parentwidth)
imgwidth=parentwidth
}else{
imgwidth=imgwidth/ (imgheight/parentheight)
imgheight=parentheight
}
}
conststyle=el.style
style.position='absolute'
style.width=imgwidth+'px'
style.height=imgheight+'px'
style.left= (parentwidth-imgwidth) /2+'px'
style.top= (parentheight-imgheight) /2+'px'
style.visibility='visible'
}
exportdefaultfunctionpositionImg(el) {
el.removeAttribute('style')
if(el.getAttribute('noPosition') ==='') {
el.style.visibility='visible'
return
}
el.removeAttribute('style')
constimg=newImage()
img.onload=function() {
position(el,img)
}
img.src=el.src
}
