SOURCE

let cropperProcessing = true
let promise = new Promise((resolve, reject) => {
    // 阻塞上传，开始裁剪图片
    let count = 0
    let runLoop = () => {
        if (cropperProcessing) {
            count++
            console.log(`第${count}次阻塞中，等待处理上传，还没resolve`)
            setTimeout(runLoop, 300)
        } else {
            // 处理图片完成，将图片递给uploader，释放阻塞上传
            resolve(count)
        }
    }
    runLoop()
})

promise && promise.then(final => { console.log(`阻塞释放，resolve在${final}次`) })

<button onclick='cropperProcessing=false'>点我继续上传</button>