[Bug Report] How do use debounce in transfer serarch?

[zhoufanglu]

Element UI version

2.15.3

Vue version

2.6.14

Steps to reproduce

import debounce from '...js'
filterMethod: debounce(function(query, item) {
            if (!query) {
              return item
            } else {
              return item.orgName.indexOf(query) !== -1
            }
          }
      )

What is Expected?

How do use debounce in transfer serarch?

What is actually happening?