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https://github.com/cjus/jsquiz

JavaScript Test
https://github.com/cjus/jsquiz

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JavaScript Test

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# JSQuiz



JavaScript Test.  Clone this REPO and provide your answers.



### 1. Tell me about strings in JavaScript

> your answer



### 2. People say that almost everything in JavaScript is an object. What things are not objects?

> your answer



### 3. How can errors be handled in JavaScript?

> your answer



### 4. Why use strict mode?

> your answer



### 5. Code an example of a for in loop?

> your answer



### 6. Code an example of an object

> your answer



### 7. Sort the following array by value:

```

var ar = [

    {text:"one", value:1},

    {text:"four", value:4},

    {text:"two", value:2},

    {text:"three", value:3},

    {text:"six", value:6}

];

```

> your answer



### 8. In this code what is the resulting value of `a`?

```

    var a=1;

    delete a;

```    

> your answer



### 9. In this code what is the resulting value of 'obj.x'?

```

	var obj = {x: 1};

	delete obj.x;

```

> your answer



### 10. Write a program which given a list of name returns the total number of unique names.

#### For example: ['bob','jill','bill','bob','sue','jill'], should return 4.

> your answer



### 11. Write an example of a self executing JavaScript module.

#### Also known as an iife (Immediately-invoked function expression)

> your answer



### 12. What does the following code do?



```

function(array, obj, iterator, context) {

    iterator = lookupIterator(iterator);

    var value = iterator.call(context, obj);

    var low = 0, high = array.length;

    while (low < high) {

      var mid = (low + high) >>> 1;

      iterator.call(context, array[mid]) < value ? low = mid + 1 : high = mid;

    }

    return low;

  };

```

> your answer



### 13. In the example above what is the role of: >>> 1

> your answer



#### 14. What value will be displayed in the alert?



```

function() {

    if(true) {

        var a = 5;

    }

    alert(a);

}

```

> your answer



### 15. What will alert display in this example?



```

function first() {

    window.a = 3;

}



function second() {

    alert(a);

}



first();

second();

```

> your answer



### 16. What are the three numbers displayed using the code below?



```

var a = 6;

function test() {

    var a = 7;

    function again() {

        var a = 8;

        alert(a);

    }

    again();

    alert(a);

}

test();

​alert(a);​

```

> your answer



### 17. What is the output below

```

function getFunc() {

    var a = 7;

    return function(b) {

        alert(a+b);

    }

}

var f = getFunc();

f(5);

```

> your answer



### 18. What does alert return below?



```

var foo = new Object();

var bar = new Object();

var map = new Object();



map[foo] = "foo";

map[bar] = "bar";



alert(map[foo]);  // what will this display??

```



> your answer



### 19. Consider what each block below returns via alert() and explain why



```

function foo() { return 1; }



alert(foo());   // what will this alert?



function foo() { return 2; }

```



```

var foo = function() { return 1; }



alert(foo());   // what will this alert?



foo = function() { return 2; }

```



> your answer



### 20. What's wrong with this code?



```

function foo()  {

   function bar(a) {

        i = 6;

   }

   for (var i=0; i<10; i += 1) {

       bar(i*2);

   }

}



foo();

```



> your answer



### 21. What happens when you set the length of an array? 

```

list.length = 4

```

> your answer



### 22. How does variable scoping work in JavaScript?  How is it different from other languages?



> your answer



### 23. How is JavaScript different from other programming languages?



> your answer



### 24. Would you say that JavaScript is an easy language to learn or a hard one? Why?



> your answer



### 25. What feature of another language would you like to see in JavaScript? How would you go about adding it to JavaScript?



> your answer



### 26. What would you say is the single most important feature of JavaScript and why?



> your answer



### 27. Provide an example of a misunderstood feature of JavaScript.



> your answer