转换为布尔型
Boolean(内容)
"", 0, undefined, null, false, NaN转换为布尔值都是false, 其余则为true
js
console.log(Boolean("字符串"))
// true
console.log(Boolean(""))
// false
console.log(Boolean(0))
// false
console.log(Boolean(90))
// true
console.log(Boolean(-1))
// true
console.log(Boolean(undefined))
// false
console.log(Boolean(null))
// false
console.log(Boolean(NaN))
// false