javascript - Recursive function call wrapped in anonymous function can't be found

Question

Note: This is mostly a theoretical practice.

function one() {
    return [1, function() { one(); }];
}
console.log((one()[1])());

The output gives undefined. Why?

Answer 1

拆分它：

function one() {
    return [1, function() { one(); }];
}
console.log((one()[1])());

one(); // [1, function() { one(); }]
[1] // function() { one(); }
() // undefined

如果您返回one()，它将返回数组：

function one() {
    return [1, function() { return one(); }];
}
console.log((one()[1])());

one(); // [1, function() { return one(); }]
[1] // function() { return one(); }
() // [1, function() { return one(); }]