i++与++i
var a, i=1;
a = i ++ //将i的值赋给a , 即a = i,之后再执行i = i + 1;
console.log(a,"i++");
console.log(i,"i++");
var a, i=1;
a = ++ i //将i+1 的值赋给a,即a = i + 1 ,之后再执行i = i + 1;
console.log(a,"++i");
console.log(i,"++i");
1:后置++ 是将自身的值赋给变量,之后自身再加1;
2:前置++ 是将自身+1 后的值赋给变量,同时自身加1;
=+与+=
var a, i=1;
a =+ i //类似直接赋值
console.log(a,"=+i"); //1
console.log(i,"=+i"); //1
var a, i=1;
a += i //a = a + i有运算操作,先做+=i运算,在赋值给a,不过此运算不改变i的原始值
console.log(a,"+=i"); //2
console.log(i,"+=i"); //1
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