原本我是這樣定義圖示字型的：（省略woff字型編碼）

@font-face {font-family: YDUI-ICONS;
  src: url('../../fonts/iconfont/iconfont.eot?t=1542201734648');
  src: url('../../fonts/iconfont/iconfont.eot?t=1542201734648#iefix') format('embedded-opentype'),
  url('data:application/x-font-woff;charset=utf-8;base64,...) format('woff'),
  url('../../fonts/iconfont/iconfont.ttf?t=1542201734648') format('truetype'),
  url('../../fonts/iconfont/iconfont.svg?t=1542201734648#iconfont') format('svg');
 
}

然後專案的圖示一直是小方框，百思不得其解：

然後把woff格式的字型去掉，就可以了：

@font-face {font-family: YDUI-ICONS;
  src: url('../../fonts/iconfont/iconfont.eot?t=1542201734648');
  src: url('../../fonts/iconfont/iconfont.eot?t=1542201734648#iefix') format('embedded-opentype'),
  url('../../fonts/iconfont/iconfont.ttf?t=1542201734648') format('truetype'),
  url('../../fonts/iconfont/iconfont.svg?t=1542201734648#iconfont') format('svg')
 
;
}

效果：