react-native RNFS不会以base64格式将文件写为doc文件

如何解决react-native RNFS不会以base64格式将文件写为doc文件

我正在尝试以base64格式保存docx文件，但该文件未保存（没有错误或异常），但已正确共享

import * as RNFS from 'react-native-fs';
import Share from 'react-native-share';

let file = {
    name: "test.docx",content: "..."    // base64 encoded file
}
RNFS.writeFile( `${ RNFS.DocumentDirectoryPath }/${ file.name }`,file.content,"base64")
    .then( result => {
        console.log( result );  // output: undefined
        Share.open({
            url: file.content,title: "Share File",message: "share file",failOnCancel: false
        })
        .then( result => {
            // after sharing file
        })
    })