javascript - 连接字符串时如何引用数组元素？

Question

如果我有:

var b1 = ["B", "V"];

我可以访问"V"与 b1[1] ;

为什么以下不起作用:

console.log(("b"+1)[1]);

我在控制台中得到 1。

Answer 1

如果b1是在全局范围内定义的，则可以将其作为窗口对象的成员进行访问:

// When variable is defined in global scope
var b1 = ["B", "V"];
console.log(window['b'+1][1]);

// Inside a function you're stuck with eval.
// You should be really, really careful with eval.
// Most likely you can change your design so you wont need it.
function test() {
  var b2 = ["B", "V"];
  console.log(eval(('b'+1))[1]);
}

test();

// Just to demonstrate that accessing an object's properties
// always works the same way
window['console']['log']('hi');