在app.vue中添加以下样式和js

<template>
  <div id="app">
    <router-view></router-view>
  </div>
</template>

<script>

(function () {
  if (
    typeof WeixinJSBridge == "object" &&
    typeof WeixinJSBridge.invoke == "function"
  ) {
    handleFontSize();
  } else {
    if (document.addEventListener) {
      document.addEventListener("WeixinJSBridgeReady", handleFontSize, false);
    } else if (document.attachEvent) {
      document.attachEvent("WeixinJSBridgeReady", handleFontSize);
      document.attachEvent("onWeixinJSBridgeReady", handleFontSize);
    }
  }

  function handleFontSize() {
    // 设置网页字体为默认大小
    WeixinJSBridge.invoke("setFontSizeCallback", { fontSize: 0 });
    // 重写设置网页字体大小的事件
    WeixinJSBridge.on("menu:setfont", function () {
      WeixinJSBridge.invoke("setFontSizeCallback", { fontSize: 0 });
    });
  }
})();
export default {}
</script>

<style lang="less">
#app {
  width: 100%;
  height: 100%;
}
body {
  // ios
  -webkit-text-size-adjust: 100% !important;
  text-size-adjust: 100% !important;
  -moz-text-size-adjust: 100% !important;
}
</style>