html5页面rem布局适配分析

!(function(win, doc){
 function setFontSize() {
  // 获取window 宽度
  // zepto实现 $(window).width()就是这么干的
  var winWidth = window.innerWidth;
  // doc.documentElement.style.fontSize = (winWidth / 640) * 100 + 'px' ;
  
  // 640宽度以上进行限制 需要css进行配合
  var size = (winWidth / 640) * 100;
  doc.documentElement.style.fontSize = (size < 100 ? size : 100) + 'px' ;
 }

 var evt = 'onorientationchange' in win ? 'orientationchange' : 'resize';

 var timer = null;

 win.addEventListener(evt, function () {
  clearTimeout(timer);

  timer = setTimeout(setFontSize, 300);
 }, false);

 win.addEventListener("pageshow", function(e) {
  if (e.persisted) {
   clearTimeout(timer);

   timer = setTimeout(setFontSize, 300);
  }
 }, false);
 // 初始化
 setFontSize();

}(window, document));

(function(WIN) {
  var setFontSize = WIN.setFontSize = function (_width) {
    var docEl = document.documentElement; 
    // 获取当前窗口的宽度
    var width = _width || docEl.clientWidth; // docEl.getBoundingClientRect().width;

    // 大于 1080px 按 1080
    if (width > 1080) { 
      width = 1080;
    }

    var rem = width / 10;
    console.log(rem);

    docEl.style.fontSize = rem + 'px';

    // 误差、兼容性处理
    var actualSize = win.getComputedStyle && parseFloat(win.getComputedStyle(docEl)["font-size"]);
    if (actualSize !== rem && actualSize > 0 && Math.abs(actualSize - rem) > 1) {
      var remScaled = rem * rem / actualSize;
      docEl.style.fontSize = remScaled + 'px';
    }
  }

  var timer;

  function dbcRefresh() {
    clearTimeout(timer);
    timer = setTimeout(setFontSize, 100);
  }

  //窗口更新动态改变 font-size
  WIN.addEventListener('resize', dbcRefresh, false);
  //页面显示时计算一次
  WIN.addEventListener('pageshow', function(e) {
    if (e.persisted) { 
      dbcRefresh() 
    }
  }, false);
  setFontSize();
})(window)


//对H5活动推过页面，宽高比例有所要求，可适当调整

function adjustWarp(warpId = '#warp') {

  const $win = $(window);
  const height = $win.height();
  let width = $win.width();

  // 考虑导航栏情况
  if (width / height < 360 / 600) {
    return;
  }

  width = Math.ceil(height * 360 / 640);

  $(warpId).css({
    height,
    width,
    postion: 'relative',
    top: 0,
    left: 'auto',
    margin: '0 auto'
  });

  // 重新计算 rem
  window.setFontSize(width);
}

@media screen and ( min-width: 320px){html{font-size:50px}}
@media screen and ( min-width: 360px){html{font-size:56.25px}}
@media screen and ( min-width: 375px){html{font-size:58.59375px}}
@media screen and ( min-width: 384px){html{font-size:60px}}
@media screen and ( min-width: 400px){html{font-size:62.5px}}
@media screen and ( min-width: 414px){html{font-size:64.6875px}}
@media screen and ( min-width: 424px){html{font-size:66.25px}}
@media screen and ( min-width: 480px){html{font-size:75px}}
@media screen and ( min-width: 540px){html{font-size:84.375px}}
@media screen and ( min-width: 640px){html{font-size:100px}}