one-mutation:通过`MutationObserver`观察一个突变，然后解决一个Promise

单突变 通过MutationObserver观察一个突变，然后解决一个Promise。 安装 npm install one-mutation // This module is only offered as a ES Module import oneMutation from 'one-mutation' ; 用法 oneMutation ( document . body , { childList : true } ) . then ( mutations => { // A text node was added! } ) ; document . body . append ( 'Text' ) ; oneMutation ( document . body , { childList : true , filter : mutations => mutat