网上的一些javascript测试题，看你能对几道题？
http://dmitrysoshnikov.com/ecmascript/the-quiz/
1. What’s the result of:
typeof typeof(null)
A) “undefined”
B) SyntaxError
C)“string”
D) “object”
E) TypeError
2. Are the algorithms of the following checks completely equvalent?
typeof foo == 'undefined'
and
typeof foo === 'undefined'
A) Yes
B) No
3. What’s the result of:
100['toString']['length']
A)100
B) 3
C) 1
D) 8
E) 0
F) SyntaxError
4. What’s the result of:
var a = (1,5 - 1) * 2
A) 0.999999999
B) 1
C) 0.5
D) 8
E) -0.5
F) 4
5. What’s the result of:
var x = 10;
var foo = {
x: 20,
bar: function () {
var x = 30;
return this.x;
}
};
console.log(
foo.bar(),
(foo.bar)(),
(foo.bar = foo.bar)(),
(foo.bar, foo.bar)()
);
A) 20, 20, 20, 20
B) 20, 20, 10, 10
C) 20, 20, 20, 10
D) 20, 20, 10, 30
E) 20, 10, 10, 10
F) 20, 10, 30, SyntaxError
6. What’s the result of:
function f(x, y) {
x = 10;
console.log(
arguments[0],
arguments[1]
);
}
f();
A) 10, null
B) 10, undefined
C) undefined, undefined
D) 10, NaN
E) 10, 10
7. What’s the result of:
var
b = 10,
c = (
20,
function (x) { return x + 100},
function () { return arguments[0]}
);
a = b + c
({x: 10}).x
A) 30, 10
B) 20
C) 10
D) 30, 110
E) NaN, 10
8. What’s the result of:
1..z
A) SyntaxError
B) New Range object (equivalent to new Range(1, ‘z’)) including all numbers and letters
C) undefined
D) Error of Range object (incompatible types for range: number and string)
E) ReferenceError “z” is not defined
9. What’s the result of:
({
x: 10,
foo: function () {
function bar() {
console.log(x);
console.log(y);
console.log(this.x);
}
with (this) {
var x = 20;
var y = 30;
bar.call(this);
}
}
}).foo();
A) 20, 30, 20
B) 10, 30, 10
C) 20, undefined, 10
D) undefined, 30, 20
E) SyntaxError
F) 20, 30, 10
10. What’s the result of:
foreach (k in {a: 10, b: 20})
{
// ...
}
A) Always SyntaxError
B) ReferenceError or possibly no error
C) Always ReferenceError
D) Iteration over the object values
E) Iteration over the object keys
F) TypeError or possibly SyntaxError