first commit

src/tool/flexible.js

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+let flexible = (designWidth, maxWidth) =>{
+    var doc = document, win = window, docEl = doc.documentElement, remStyle = document.createElement("style"), tid;
+    designWidth = designWidth || 1440;
+    maxWidth = maxWidth || 1440;
+    function refreshRem() {
+        var width = docEl.getBoundingClientRect().width;
+        maxWidth = maxWidth || 1440;
+        width > maxWidth && (width = maxWidth);
+        var rem = width * 10 / designWidth;
+        remStyle.innerHTML = 'html{font-size:' + rem + 'px;}';
+    }
+    if (docEl.firstElementChild) {
+        docEl.firstElementChild.appendChild(remStyle);
+    } else {
+        var wrap = doc.createElement("div");
+        wrap.appendChild(remStyle);
+        doc.write(wrap.innerHTML);
+        wrap = null;
+    }
+    //要等 wiewport 设置好后才能执行 refreshRem，不然 refreshRem 会执行2次；
+    refreshRem();
+    win.addEventListener("resize", function() {
+        clearTimeout(tid); //防止执行两次
+        tid = setTimeout(refreshRem, 300);
+    }, false);
+
+    win.addEventListener("pageshow", function(e) {
+        if (e.persisted) { // 浏览器后退的时候重新计算
+            clearTimeout(tid);
+            tid = setTimeout(refreshRem, 300);
+        }
+    }, false);
+
+    if (doc.readyState === "complete") {
+        doc.body.style.fontSize = "16px";
+    } else {
+        doc.addEventListener("DOMContentLoaded", function(e) {
+            doc.body.style.fontSize = "16px";
+        }, false);
+    }
+};
+
+export default flexible