javascript - ES7 async和await方法使用問題

Question

#想利用await關鍵字把回傳的url賦給url變數
但是console.log一直打出undefined

uploadImgReq方法程式碼如下:

uploadImgReq: function(file) {
                var nameKey = this.generateUUID();
                // event.target.files[0].name = nameKey;
                this.$http.get(this.url + '/qiniu/token', {
                    params: {
                        key: nameKey
                    }
                }).then((response) => {
                    this.token = response.data.data.token;
                    if (this.token != null) {
                        var formData = new FormData();
                        formData.append('file', file);
                        formData.append('key', nameKey);
                        formData.append('token', this.token);
                        this.$http.post('http://upload.qiniu.com/', formData, {
                            headers: {
                                'Content-Type': 'multipart/form-data'
                            }
                        }).then((response) => {
                            if (response.status == 200) {
                                this.uploadStatus = false;
                                this.$message({
                                    message: '上传成功',
                                    type: 'success'
                                });
    
                                var imgUrl = this.qiniu + response.body.key;
                                console.log("i am returned")
                                return new Promise(function (resolve, reject) {
                                    resolve(imgUrl)
                                })
                            }
                        }).catch((response) => {
    
                        })
                    }
                }).catch((response) => {
    
                })

請問各位問題出在哪裡了呢

Answer 1

this.$http.post('http://upload.qiniu.com/', formData, {
    headers: {
        'Content-Type': 'multipart/form-data'
    }
})

改為

return this.$http.post('http://upload.qiniu.com/', formData, {
    headers: {
        'Content-Type': 'multipart/form-data'
    }
})

Answer 2

uploadImgReq裡的promise沒有return

uploadImgReq: function(file) {
......
return this.$http.get(this.url + '/qiniu/token', { //没有return
......
}

另外promise.then裡不應該嵌套promise，應該return promise，然後用then鍊式呼叫的方式來