JS基礎11-3強制型別轉換Boolean
阿新 • • 發佈：2022-11-29
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/*
將其他型別轉化為Boolean
-使用Boolean()函式
數字-》布林：除了0 和 NAN都是true
字串-》布林：除了空串其餘都是true
null和undefined都是false
物件也會轉換為true
*/
// 數字-》布林：除了0 和 NAN都是true
var a = 123
a = Boolean(a)//true
console.log(a, typeof (a))
var b = -123
b = Boolean(b)//true
console.log(b, typeof (b))
var c = 0
c = Boolean(c)//false
console.log(c, typeof (c))
var d = NaN
d = Boolean(d)//false
console.log(d, typeof (d))
//字串型別轉布林值
var a2 = 'hello'
a2 = Boolean(a2)
console.log(a2, typeof (a2))//true
var b2 = ''
b2 = Boolean(b2)
console.log(b2, typeof (b2))//false
var c3 = 'true'
c3 = Boolean(c3)
console.log(c3, typeof (c3))//true
var d3 = 'false'
d3 = Boolean(d3)
console.log(d3, typeof (d3))//true
var e3 = ' '//字串裡面是空格
d3 = Boolean(e3)
console.log(d3, typeof (d3))//true
//null和undefined轉布林
var a4 = null
a4 = Boolean(a4)
console.log(a4, typeof (a4))//false
var b4 = undefined
b4 = Boolean(b4)
console.log(b4, typeof (b4))//false
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