转载-----javascript quiz
<div id="cnblogs_post_body">问题很容易看懂，所以就没有翻译.------------------------原文--------------------------------
## Intro Questions
01. When might comparative type coercion occur? How would you avoid it? How would you change a "falsy" or "truthy" value into a real boolean?
02. Describe how variable scope works. Explain how to create a closure using a self-executing anonymous function (also called IIFE: immediately-invoked function expression).
03. Explain briefly how prototypal inheritance differs from class-based, "classical" inheritance.
04. Describe how the "module pattern" works. Explain how the "revealing module pattern" expands upon it.
05. How does a client-side MVC (or MVVM) approach work? What is your preferred MV* JS framework?
## Additional Questions
06. Why do these yield different results?
```js
'1' + 2 +3 ; // Equals '123'
3+ 2 + '1'; // Equals '51'
3+ 2 +1 ; // Equals 6
```
07. Why is `0.3` *not* the result of the following addition? How do you work around this peculiarity?
```js
0.1 + 0.2; // Equals 0.30000000000000004
```
08. Describe how variable hoisting works, and how to avoid bugs that may arise from it.
09. How do these differ?
```js
function foo() {}
// versus
var foo = function() {};
```
10. When might you use a function's `call()` method, or its `apply()` method?
11. Explain how to determine if a variable is an array or an object. (*Hint:* `typeof` lies!)
12. In the following example, what is foo aliased to? (*Hint:* It is what `this` means.)
```js
(function(foo) {
// What is 'foo' aliased to?
})(this);
```
13. In JavaScript (and the DOM), some global variables are actually mutable, such as: `window`, `document`, and `undefined`. How would you write code to ensure these were predictably available for use? Assuming someone had injected this code, how would you work around it? (*Hint:* See the previous question.)
```js
var window = '';
var document = 0;
var undefined = true;
```
14. In one line of code, how you would make a copy of an array?
15. What is the difference between `setInterval` and `setTimeout`? *Bonus:* What is the lowest cross-browser increment that each can accurately use?
16. Explain how `delete` works. What types of things cannot be deleted?
17. Describe how event delegation works, and when you should use it to handle UI interaction. Example markup&hellip;
```html
<ul id="special">
<li>
<a href="#">Special link 1</a>
</li>
<li>
<a href="#">Special link 2</a>
</li>
<li>
<a href="#">Special link 3</a>
</li>
</ul>
```
18. What does this snippet of code do?
```js
var foo = bar ? bar : 0;
```
19. When might you write something like this, and what is it shorthand for?
```js
foo && foo.bar();
```
20. How do `parseInt` and `parseFloat` differ? When would you use a number's `toFixed()` method? In what instance might the following code snippet actually make sense to use?
```js
var my_number = my_string - 0;
```
21. Write a function named `sum` that returns the total of any number of parameters. Example&hellip;
```js
// Should equal 15
sum(1, 2, 3, 4, 5);
// Should equal 0
sum(5, null, -5);
// Should equal 10
sum('1.0', false, 1, true, 1, 'A', 1, 'B', 1, 'C', 1, 'D', 1, 'E', 1, 'F', 1, 'G', 1);
// Should equal 0.3, not 0.30000000000000004
sum(0.1, 0.2);
```
ANSWERS：http://www.cnblogs.com/chenguangyin/archive/2012/11/24/2786129.html
原文地址：https://github.com/nathansmith/javascript-quiz
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