vue使用axios向后端发送请求。默认是异步发送请求。
    例如：
      

handleSubmitTest(systemId) {
    fetchGetProjectInfoBySystemId(systemId).then(response => {
        const projectObj = response.data.data
        const branchObj = this.getBranchInfoByProjectId(projectObj.id)
        console.log('test2')
    })
}
getBranchInfoByProjectId(projectId) {
    const branchObj = fetchGetBranchInfoByProjectId(projectId).then(response => {
        console.log('test1')
        return response.data.data
    })
    return branchObj
}

    上述代码执行结果:
    先输出test2，再输出test1。
    
    要想保证先同步执行，需要添加async、await组合。
        

handleSubmitTest(systemId) {
    fetchGetProjectInfoBySystemId(systemId).then(async response => {
        const projectObj = response.data.data
        const branchObj = await this.getBranchInfoByProjectId(projectObj.id)
        console.log('test2')
    })
}
getBranchInfoByProjectId(projectId) {
    const branch Obj = fetchGetBranchInfoByProjectId(projectId).then(response => {
        console.log('test1')
        return response.data.data
    })
    return branchObj
}

    上述代码执行结果:
    先输出test1，再输出test2。
    加上async、await组合。保证程序同步执行。
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    上述代码还可以有另外一种写法：
        

async handleSubmitTest(systemId) {
    const projectObj = await this.getProjectInfoBySystemId(systemId)
        const branchObj = await this.getBranchInfoByProjectId(projectObj.id)
        console.log('test2')
    }
getProjectInfoBySystemId(systemId) {
    const projectObj = fetchGetProjectInfoBySystemId(systemId).then(response => {
        return response.data.data
    })
    return projectObj
}
getBranchInfoByProjectId(projectId) {
    const branch Obj = fetchGetBranchInfoByProjectId(projectId).then(response => {
        console.log('test1')
        return response.data.data
    })
    return branchObj
}