js面试题

Js中有不少容易被忽略的细节问题，自己搜集了些面试题，在此分享出来，供君共勉之。

(function () {  
return typeof arguments;  
})();  
A. "object"
B. "array"
C. "arguments"
D. "undefined"

var f = function g() {
    return 23;
};
typeof g();
A. "number"
B. "undefined"
C. "function"
D. Eorror

(function (x) {
delete x;
return x;
})(1);
A. 1
B. null
C. undefined
D. Error

var y = 1,
x = y = typeof x;
x;
A. 1
B. "number"
C. undefined
D. "undefined" 

(function f(f) {
return typeof f();
})(function () {
return 1;
});
A. "number"
B. "undefined"
C. "function"
D. Error

var foo = {
bar: function () {
    return this.baz;
},
baz: 1
};
(function () {
return typeof arguments[0]();
})(foo.bar);
A. "undefined"
B. "object"
C. "number"
D. "function"

var foo = {
bar: function () {
    return this.baz;
},
baz: 1
};
typeof (f = foo.bar)();
A. "undefined"
B. "object"
C. "number"
D. "function"

var f = (function f() {
return "1";
}, function g() {
return 2;
})();
typeof f;
A. "string"
B. "number"
C. "function"
D. "undefined"

var x = 1;
if (function f() {}) {
x += typeof f;
}
x;
A. 1
B. "1function"
C. "1undefined"
D. NaN

var x = [typeof x, typeof y][1];
typeof typeof x;
A. "number"
B. "string"
C. "undefined"
D. "object"

(function (foo) {
return typeof foo.bar;
})({
foo: {
    bar: 1
}
});
A、“undefined” 
B、“object” 
C、“number” 
D、Error

(function f() {
function f() {
    return 1;
}
return f();
function f() {
    return 2;
}
})();
A、1 
B、2 
C、Error (e.g. “Too much recursion”) 
D、undefined

function f() {
return f;
}
new f() instanceof f;
A、true 
B、false