JavaScript基础题--变量

-------------------<<JavaScript基础题>>-------------------
if (!("a" in window)) {
var a = 1;
}
console.log(a);
console.log(c);
----------------------------------------
if ("a" in window) {
var a = 1;
}
console.log(a);
console.log(c);
-----------------------------------------
if (!("a" in window)) {
var c = 1;
}
console.log(a);
console.log(c);
-----------------------------------------
if (!("a" in window)) {
var c = 1;
}
console.log(a);
console.log(c);
-----------------------------------------
----------注：每段代码在console里运行前需刷新页面---------
------------------------能搞明白a,c值的缘由 -----------------------
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