promise封装异步函数

function parseJson(file) {
            return new Promise(
                (resolve, reject) => {
                    const reader = new FileReader();
                    reader.addEventListener('load', function(ev) {
                        try {
                            const obj = JSON.parse(ev.target.result);
                            resolve(obj)
                        } catch (error) {
                            reject(error)
                        }
                    })
                    reader.readAsText(file)
                }
            )
        }

        async function toParse(target) {
            const data = await parseJson(target.files[0]);
            console.log(data)
        }