在JS中使用eval时,我遇到了奇怪的行为.
var f = function () {
var x = 10;
return function () {
eval('console.log(x);');
window['eval']('console.log(x);');
}
};
f()();
OUTPUT：
10
undefined:1
console.log(x);
^
ReferenceError: x is not defined
为什么使用eval显式捕获x但全局[‘eval’]没有？
即使全局[‘eval’]没有捕获x,为什么它在eval之后无法看到,它已经捕获了x？
解决方法
window [‘eval’]在全局范围内运行,eval()在本地范围内运行.
来自Mozilla的Javascript参考：
If you use the eval function indirectly,by invoking it via a
reference other than eval,as of ECMAScript 5 it works at global scope
rather than local scope; this means,for instance,that function
declarations create global functions,and that the code being
evaluated doesn’t have access to local variables within the scope
where it’s being called.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval
