我要做一個檢測undefined值的 代碼: data = { highscore: 0, localStorage: null, footsteps: 0, start: 0, checkin: 0, health: 6, fed: 0, birthday: Date.now(), feedCount: 0, pet_push_time: 0, old_pet_mod: false, old_pet_birthday: Date.now(), old_pet_days: -1, old_pet_pet_push_time: 0, old_pet_feedCount: 0, back_HPbox: 0, } function undefined_test(val) { if (val === undefined){ return 1 } else { return 0 } //1表示這個值未定義 } undefined_test(data.test); 他不會回傳1
我把它改成這樣就好了 ``` function undefined_test(val) { if (val == null || val === undefined) { return 1 } else { return 0 } }
我剛測試,正常呀 有回傳1呀 看這邊 https://jsfiddle.net/poopoo888888/4qstLuye/1/