你即將離開本站

並前往https://www.w3schools.com/jsref/jsref_undefined.asp

JavaScript undefined Property - W3Schools

Definition and Usage ... The undefined property indicates that a variable has not been assigned a value, or not declared at all. Browser Support. Property.

確定！ 回上一頁

查詢 「JS if undefined」的人也找了：

  1. js undefined判斷
    2.
  2. JS if undefined
    3.
  3. JS undefined
    4.
  4. undefined
    5.
  5. JavaScript check undefined or null
    6.
  6. javascript undefined
    7.
  7. undefined js判定
    8.
  8. Js return undefined
    9.