/* 自執行匿名函式,隨著螢幕大小的變化而變化 */
(function () {
    // deicePixelRatio ：裝置畫素
var scale = 1 / devicePixelRatio;
//設定meta 壓縮介面 模擬裝置的高解析度
document.querySelector('meta[name="viewport"]').setAttribute('content', 'initial-scale=' + scale + ', maximum-scale=' + scale + ', minimum-scale=' + scale + ', user-scalable=no');
 
//debounce 為節流函式，自己實現。或者引入underscoure即可。
    /* Begin */
var _ = function(obj) {
        if (obj instanceof _) return obj;
if (!(this instanceof _)) return new _(obj);
this._wrapped = obj;
};
_.now = Date.now || function() {
            return new Date().getTime();
};
_.debounce = function(func, wait, immediate) {
        var 
 
timeout, args, context, timestamp, result;
var later = function() {
            var last = _.now() - timestamp;
if (last < wait && last >= 0) {
                timeout = setTimeout(later, wait - last);
} else {
                timeout = null;
if (!immediate) {
                    result = func.apply(context, 
 
args);
if (!timeout) context = args = null;
}
            }
        };
return function() {
            context = this;
args = arguments;
timestamp = _.now();
var callNow = immediate && !timeout;
if (!timeout) timeout = setTimeout(later, wait);
if (callNow) {
                result = func.apply(context, args);
context = args = null;
}
            return result;
};
};
/* End */
var reSize = _.debounce(function () {
        var deviceWidth = document.documentElement.clientWidth > 750 ? 750 : document.documentElement.clientWidth;
//按照750畫素下字型為100px的標準來，得到一個字型縮放比例值 7.5
document.documentElement.style.fontSize = (deviceWidth / 7.5) + 'px';
console.log(document.documentElement.style.fontSize);
}, 50);
window.onresize = reSize;
})();