监听fetch的方法

重新封装fetch

function onFetch(callback) {
    let logFetch = window.fetch
    window.fetch = function (input, init) {
        return new Promise((resolve, reject) => {
            logFetch(input, init)
                .then(function (response) {
                    callback(response)
                    resolve(response)
                }, reject)
        })
    }
}

调用onFetch方法

onFetch(response => {
    response.json()
    .then(res=>{
		console.log(res)
	})
})