metaHandle：移动端适配viewport代码

viewport.js

define(function(require, exports, module) {

  var ua = navigator.userAgent,
    android = ua.match(/(Android);?[\s\/]+([\d.]+)?/),
    ipad = ua.match(/(iPad).*OS\s([\d_]+)/),
    ipod = ua.match(/(iPod)(.*OS\s([\d_]+))?/),
    iphone = !ipad && ua.match(/(iPhone\sOS)\s([\d_]+)/),
    os = {};

  if (android) os.android = true, os.version = android[2];
  if (iphone && !ipod) os.ios = os.iphone = true, os.version = iphone[2].replace(/_/g, '.')
  if (ipad) os.ios = os.ipad = true, os.version = ipad[2].replace(/_/g, '.')
  if (ipod) os.ios = os.ipod = true, os.version = ipod[3] ? ipod[3].replace(/_/g, '.') : null;

  var MetaHandler = function(){
    //MONOSTATE
    if(MetaHandler.prototype.instance){
      return MetaHandler.prototype.instance;
    }
    var me = this;
    var meta = {},_els;

    /**
     * 初始化
     * _els
     * meta = {name:{content:String,seriation:Array,store:{property:String},...},...}
     * @method init
     */
    function init(){
      _els = document.getElementsByTagName('meta');
      for(var i=0;i<_els.length;i++){
        var name = _els[i].name;
        if(name){
          meta[name] = {};
          meta[name].el = _els[i];
          meta[name].content = _els[i].content;
          meta[name].seriation = meta[name].content.split(',');
          meta[name].store = getContentStore(name);
        }
      }
      return me;
    }
    function getContentStore(name){
      var content = meta[name].seriation,store = {};
      for(var i=0;i<content.length;i++){
        if(content[i].length<1){
          content[i] = null;
          delete content[i];
          content.length--;
        }else{
          var ct = content[i].split('='),
            pp = ct[0];
          if(pp){
            store[pp] = ct[1];
          }
        }
      }
      return store;
    }
    this.hasMeta = function(name){
      return meta[name]?1:0;
    }
    this.createMeta = function(name){
      if(!this.hasMeta(name)){
        var el = document.createElement('meta');
        el.name = name;
        document.head.appendChild(el);
        meta[name] = {};
        meta[name].el = el;
        meta[name].content = '';
        meta[name].seriation = [];
        meta[name].store = {};
      }
      return me;
    }
    this.setContent = function(name,value){
      meta[name].content = value;
      meta[name].el.content = value;
      return me;
    }
    this.getContent = function(name){
      return meta[name] && meta[name].content;
    }
    function updateContent(name){
      meta[name].content = meta[name].seriation.join(',');
      me.setContent(name,meta[name].content);
      return me;
    }
    this.removeContentProperty = function(name,property){
      var _property = property;
      if(meta[name]){
        if(meta[name].store[_property]!=null){
          for(var i = 0;i<meta[name].seriation.length;i++){
            if(meta[name].seriation[i].indexOf(property+'=')!=-1){
              meta[name].seriation[i] = null;
              delete meta[name].seriation[i];
              break;
            }
          }
        }
        updateContent(name);
      }
      return me;
    }
    this.getContentProperty = function(name,property){
      return meta[name] && meta[name].store[property];
    }
    this.setContentProperty = function(name,property,value){
      var _property = property,
        pv = property+'='+value;
      if(meta[name]){
        if(meta[name].store[_property]!=null){
          meta[name].store[_property] = value;
          for(var i = 0;i<meta[name].seriation.length;i++){
            if(meta[name].seriation[i].indexOf(property+'=')!=-1){
              meta[name].seriation[i] = pv;
              break;
            }
          }
        }else{
          meta[name].store[_property] = value;
          meta[name].seriation.push(pv);
        }
        updateContent(name);
      }
      return me;
    }
    this.fixViewportWidth = function(width){
      width = width || me.getContentProperty('viewport','width');
      if(width != 'device-width'){
        var iw = window.innerWidth || width,
          ow = window.outerHeight || iw,
          sw = window.screen.width || iw,
          saw = window.screen.availWidth || iw,
          ih = window.innerHeight || width,
          oh = window.outerHeight || ih,
          ish = window.screen.height || ih,
          sah = window.screen.availHeight || ih,
          w = Math.min(iw,ow,sw,saw,ih,oh,ish,sah),
          ratio = w/width,
          dpr = window.devicePixelRatio,
          ratio = Math.min(ratio,dpr);

        if(os.android){
          me.removeContentProperty('viewport','user-scalable');
          me.setContentProperty('viewport','initial-scale',ratio);
          me.setContentProperty('viewport','maximum-scale',ratio);
        }else if(os.ios && !os.android){
          me.setContentProperty('viewport','user-scalable','no');
          if($.os.ios && parseInt($.os.version)<7){
            Core.MetaHandler.setContentProperty('viewport','initial-scale',ratio);
          }
        }
      }
    }
    init();
    //MONOSTATE
    MetaHandler.prototype.instance = this;
  };

  return new MetaHandler;
});