Painful JavaScript syntax features
- 2020-03-30 04:02:55
- OfStack
In zhihu see someone published and javascript related questions, and share with you, although it is a long time ago, but these questions are quite classic, inevitably let people feel that javascript is really a pain in the language.
1.
(function () {
return typeof arguments;
})();
A. "object"
B. "array"
C. "arguments"
D. "undefined"
Answer: A,
2.
var f = function g() {
return 23;
};
typeof g();
A. "number"
B. "undefined"
C. "function"
D. Eorror
Answer: D
3.
(function (x) {
delete x;
return x;
})(1);
A. 1
B. null
C. undefined
D. Error
Answer: A,
4.
var y = 1,
x = y = typeof x;
x;
A. 1
B. "number"
C. undefined
D. "undefined"
Answer: D
5.
(function f(f) {
return typeof f();
})(function () {
return 1;
});
A. "number"
B. "undefined"
C. "function"
D. Error
Answer: A,
6.
var foo = {
bar: function () {
return this.baz;
},
baz: 1
};
(function () {
return typeof arguments[0]();
})(foo.bar);
A. "undefined"
B. "object"
C. "number"
D. "function"
Answer: A,
7.
var foo = {
bar: function () {
return this.baz;
},
baz: 1
};
typeof (f = foo.bar)();
A. "undefined"
B. "object"
C. "number"
D. "function"
Answer: A,
8.
var f = (function f() {
return "1";
}, function g() {
return 2;
})();
typeof f;
A. "string"
B. "number"
C. "function"
D. "undefined"
Answer: B
9.
var x = 1;
if (function f() {}) {
x += typeof f;
}
x;
A. 1
B. "1function"
C. "1undefined"
D. NaN
Answer: C
10.
var x = [typeof x, typeof y][1];
typeof typeof x;
A. "number"
B. "string"
C. "undefined"
D. "object"
Answer: B
11.
(function (foo) {
return typeof foo.bar;
})({
foo: {
bar: 1
}
});
A ," undefined "
B ," object "
C ," number "
D , Error
Answer: A,
12.
(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
Answer: B
13.
function f() {
return f;
}
new f() instanceof f;
A , true
B , false
Answer: B
14.
with (function(x, undefined){}) length;
A , 1
B , 2
C , undefined
D , Error
Answer: B
15.
Which of the following statements produces a run error : (a)
A.var obj = ();
B.var obj = [];
C.var obj = {};
D.var obj = //;
Answer: A,