Illegal invocation with document.querySelector [duplicate]

document.querySelectorAll赋给其它变量时, 为什么要.bind(document)?

https://*.com/questions/12637061/illegal-invocation-with-document-queryselector
https://segmentfault.com/q/1010000006207891/a-1020000006208171
https://segmentfault.com/q/1010000006207891