The callback to execute when the Promise is rejected.
A Promise for the completion of the callback.
清除定时器
Attaches a callback that is invoked when the Promise is settled (fulfilled or rejected). The resolved value cannot be modified from the callback.
The callback to execute when the Promise is settled (fulfilled or rejected).
A Promise for the completion of the callback.
Attaches callbacks for the resolution and/or rejection of the Promise.
The callback to execute when the Promise is resolved.
The callback to execute when the Promise is rejected.
A Promise for the completion of which ever callback is executed.
Attaches a callback for only the rejection of the Promise.