对js逻辑运算符的理解
(a || b) === () => { if (a) {return a} else {return b} }=== (a ? a : b)
(a && b) === () => { if (a) {return b} else {return a} }=== (a ? b : a)
(a || b) === () => { if (a) {return a} else {return b} }=== (a ? a : b)
(a && b) === () => { if (a) {return b} else {return a} }=== (a ? b : a)