SAP Spartacus lock focus directive如何判斷有沒有focusable children hasFocusableChildren：傳回boolean
SAP Spartacus lock focus directive如何判斷有沒有focusable children focusable：傳回HTMLElement數組
SAP Spartacus lock focus directive如何判斷有沒有focusable children service的原本類型是LockFocusService
沒有任何實作：
SAP Spartacus lock focus directive如何判斷有沒有focusable children 再往上看TrapFocusService：
hasFocusableChildren借用了findFocusable方法，判斷傳回的數組元素是否大于0
SAP Spartacus lock focus directive如何判斷有沒有focusable children 這個find Focusable又是TabFocusService實作的：
SAP Spartacus lock focus directive如何判斷有沒有focusable children 這個selectFocusUtil又是EscapeFocusService的：
SAP Spartacus lock focus directive如何判斷有沒有focusable children 哪些是可以被focus的子元素：
SAP Spartacus lock focus directive如何判斷有沒有focusable children SAP Spartacus lock focus directive如何判斷有沒有focusable children 下列這些selector指向的元素是可以focus的：
SAP Spartacus lock focus directive如何判斷有沒有focusable children 最後調用host元素的原生query方法查詢：
SAP Spartacus lock focus directive如何判斷有沒有focusable children 
