問題描述

頁面用rem寫的，在chrome中f12測試手機的時候，都是對的。但是在真機上，安卓是對的，在蘋果手機上顯示的文字就是特別小的是為什么呢？

問題解答

這是dpr的原因，ios的有的是2倍屏，3倍屏，所以會造成“比Android”看起來小的原因，解決策略

;(function(win, lib) {

var doc = win.document;var docEl = doc.documentElement;var metaEl = doc.querySelector(’meta[name='viewport']’);var flexibleEl = doc.querySelector(’meta[name='flexible']’);var dpr = 0;var scale = 0;var tid;var flexible = lib.flexible || (lib.flexible = {});if (metaEl) { //console.warn(’將根據已有的meta標簽來設置縮放比例’); var match = metaEl.getAttribute(’content’).match(/initial-scale=([d.]+)/); if (match) {scale = parseFloat(match[1]);dpr = parseInt(1 / scale); }} else if (flexibleEl) { var content = flexibleEl.getAttribute(’content’); if (content) {var initialDpr = content.match(/initial-dpr=([d.]+)/);var maximumDpr = content.match(/maximum-dpr=([d.]+)/);if (initialDpr) { dpr = parseFloat(initialDpr[1]); scale = parseFloat((1 / dpr).toFixed(2));}if (maximumDpr) { dpr = parseFloat(maximumDpr[1]); scale = parseFloat((1 / dpr).toFixed(2));} }}if (!dpr && !scale) { var isAndroid = win.navigator.appVersion.match(/android/gi); var isIPhone = win.navigator.appVersion.match(/iphone/gi); var devicePixelRatio = win.devicePixelRatio; if (isIPhone) {// iOS下，對于2和3的屏，用2倍的方案，其余的用1倍方案if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) { dpr = 3;} else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)) { dpr = 2;} else { dpr = 1;} } else {// 其他設備下，仍舊使用1倍的方案dpr = 1; } scale = 1 / dpr;}docEl.setAttribute(’data-dpr’, dpr);if (!metaEl) { metaEl = doc.createElement(’meta’); metaEl.setAttribute(’name’, ’viewport’); metaEl.setAttribute(’content’, ’initial-scale=’ + scale + ’, maximum-scale=’ + scale + ’, minimum-scale=’ + scale + ’, user-scalable=no’); if (docEl.firstElementChild) {docEl.firstElementChild.appendChild(metaEl); } else {var wrap = doc.createElement(’p’);wrap.appendChild(metaEl);doc.write(wrap.innerHTML); }}function refreshRem() { var width = docEl.getBoundingClientRect().width; if (width / dpr > 750) {width = 750 * dpr; } var rem = width / 750 * 100; // 設計圖 750 docEl.style.fontSize = rem + ’px’; flexible.rem = win.rem = rem;}win.addEventListener(’resize’, function() { clearTimeout(tid); tid = setTimeout(refreshRem, 300);}, false);win.addEventListener(’pageshow’, function(e) { if (e.persisted) {clearTimeout(tid);tid = setTimeout(refreshRem, 300); }}, false);if (doc.readyState === ’complete’) { doc.body.style.fontSize = 12 * dpr + ’px’;} else { doc.addEventListener(’DOMContentLoaded’, function(e) {doc.body.style.fontSize = 12 * dpr + ’px’; }, false);}

refreshRem();flexible.dpr = win.dpr = dpr;flexible.refreshRem = refreshRem;flexible.rem2px = function(d) { var val = parseFloat(d) * this.rem; if (typeof d === ’string’ && d.match(/rem$/)) {val += ’px’; } return val;}flexible.px2rem = function(d) { var val = parseFloat(d) / this.rem; if (typeof d === ’string’ && d.match(/px$/)) {val += ’rem’; } return val;}

})(window, window[’lib’] || (window[’lib’] = {}));

確認一下 meta viewport 信息是否正確。

<meta name='viewport' content='width=device-width,initial-scale=1,user-scalable=no'>