function loadImg(src) {

const p = new Promise(

(resolve, reject) => {

const img = document.createElement('img')

img.onload = () => {

resolve(img)

}

img.onerror = () => {

const err = new Error(`图片加载失败 ${src}`)

reject(err)

}

img.src = src

}

)

return p

}

// const url = 'https://img.mukewang.com/5a9fc8070001a82402060220-140-140.jpg'

// loadImg(url).then(img => {

// console.log(img.width)

// return img

// }).then(img => {

// console.log(img.height)

// }).catch(ex => console.error(ex))

const url1 = 'https://img.mukewang.com/5a9fc8070001a82402060220-140-140.jpg'

const url2 = 'https://img3.mukewang.com/5a9fc8070001a82402060220-100-100.jpg'

loadImg(url1).then(img1 => {

console.log(img1.width)

return img1 // 普通对象

}).then(img1 => {

console.log(img1.height)

return loadImg(url2) // promise 实例

}).then(img2 => {

console.log(img2.width)

return img2

}).then(img2 => {

console.log(img2.height)

}).catch(ex => console.error(ex))