逗号运算符:整个表达式返回最右边表达式的值
<script>
var a,b,c,d;
a = (b = 1,c = 2,d = 3);
alert(a);
</script>
void运算符:强制制定表达式不返回值
<script>
var a,b,c,d;
a = void(b = 1,c = 2,d = 3);
alert(a);
</script>
逗号运算符:整个表达式返回最右边表达式的值
<script>
var a,b,c,d;
a = (b = 1,c = 2,d = 3);
alert(a);
</script>
void运算符:强制制定表达式不返回值
<script>
var a,b,c,d;
a = void(b = 1,c = 2,d = 3);
alert(a);
</script>