vue下載本地文件 下載二進制流文件 兼容ie

vue-cli2要下載的靜態文件放在static目錄下，vue-cli3則放在public目錄下

ie不支持 h5 的download寫法，故用以下寫法

<el-button type="text" @click="download">aa.excel</el-button>

download(){
      axios.get('static/aa.excel', {
        responseType: 'blob', 
        }).then(response => {
          if ("msSaveOrOpenBlob" in navigator) {//ie
              var data = response.data;
              var blob = new Blob([data], { type: "application/vnd.ms-excel" });
              window.navigator.msSaveOrOpenBlob(blob, 'aa.excel');
              return;
          } else {
            const url = window.URL.createObjectURL(new Blob([response.data]));
            const link = document.createElement('a');
            let fname = 'aa.excel';
            link.href = url;
            link.setAttribute('download', fname);
            document.body.appendChild(link);
            link.click();
          }
        });
    },

若不需要兼容ie瀏覽器，則可直接用h5 download

<a href="static/aa.excel" download="aa.excel">aa.excel</a>