2019-05-05

工作中遇到移动端适配的问题

!function(win) {

function resize() {

  var domWidth = domEle.getBoundingClientRect().width;

  if(domWidth / v > 540){

  domWidth = 540 * v;

  }

  win.rem = domWidth / 7.5;

  domEle.style.fontSize = win.rem + "px";

}

var v, initial_scale, timeCode, dom = win.document, domEle = dom.documentElement, viewport = dom.querySelector('meta[name="viewport"]'), flexible = dom.querySelector('meta[name="flexible"]');

if (viewport) {

  //viewport：<meta name="viewport"content="initial-scale=0.5, minimum-scale=0.5, maximum-scale=0.5,user-scalable=no,minimal-ui"/>

  var o = viewport.getAttribute("content").match(/initial\-scale=(["']?)([\d\.]+)\1?/);

  if(o){

  initial_scale = parseFloat(o[2]);

  v = parseInt(1 / initial_scale);

  }

} else {

  if (flexible) {

  var o = flexible.getAttribute("content").match(/initial\-dpr=(["']?)([\d\.]+)\1?/);

  if(o){

    v = parseFloat(o[2]);

    initial_scale = parseFloat((1 / v).toFixed(2))

  }

  }

}

if (!v && !initial_scale) {

  var n = (win.navigator.appVersion.match(/android/gi), win.navigator.appVersion.match(/iphone/gi));

  v = win.devicePixelRatio;

  v = n ? v >= 3 ? 3 : v >= 2 ? 2 : 1 : 1, initial_scale = 1 / v

}

//没有viewport标签的情况下

if (domEle.setAttribute("data-dpr", v), !viewport) {

  if (viewport = dom.createElement("meta"), viewport.setAttribute("name", "viewport"), viewport.setAttribute("content", "initial-scale=" + initial_scale + ", maximum-scale=" + initial_scale + ", minimum-scale=" + initial_scale + ", user-scalable=no"), domEle.firstElementChild) {

  domEle.firstElementChild.appendChild(viewport)

  } else {

  var m = dom.createElement("div");

  m.appendChild(viewport), dom.write(m.innerHTML)

  }

}

win.dpr = v;

win.addEventListener("resize", function() {

  clearTimeout(timeCode), timeCode = setTimeout(resize, 300)

}, false);

win.addEventListener("pageshow", function(b) {

  b.persisted && (clearTimeout(timeCode), timeCode = setTimeout(resize, 300))

}, false);

/* 个人觉得没必要完成后就把body的字体设置为12

"complete" === dom.readyState ? dom.body.style.fontSize = 12 * v + "px" : dom.addEventListener("DOMContentLoaded", function() {

  //dom.body.style.fontSize = 12 * v + "px"

}, false);

*/

resize();

}(window);