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Devin Fields - Technical Interview - Mid-level JavaScript test

by David Lomneck

HTML

<!--don't edit this file-->
<div id=question>
  <span style="font-weight:bold">Question 1:</span> Generate all prime numbers between two given numbers. The two numbers are parameters that can be passed into the function. A prime number is one that is only divisible by 1 and itself. Output the results into the results element below.
  <p>
    Example:
    <br/> Primes between 1 and 10
    <br/> Output:
    <br/> 2
    <br/> 3
    <br/> 5
    <br/> 7
    <br/>
  </p>
</div>
<br/>
<p>Your Results:</p>
<div id="results1"></div>
<br/>
<div id=question>
<span style="font-weight:bold">Question 2:</span> A positive integer is called a palindrome if its representation in the decimal system is the same when read from left to right and from right to left. For a given positive integer K of not more than 1000000 digits, write the value of the smallest
  palindrome larger than K to output. Numbers are always displayed without leading zeros.
  <P>
    Example:
    <br/> Number Given: 808
    <br/> Output: 818
    <br/> Number Given: 2133
    <br/> Output: 2222
    <br/>
  </P>
</div>
<br/>
<p>Your Results:</p>
<div id="results2"></div>
<br/>
<div id="question">
  <span style="font-weight:bold">Question 3:</span> Write a simple string compression algorithm. If a character [ch] occurs n>1 times in a row, then it will be represented by [ch][n].
  <P>
    Example:
    <br/> String Given: aaaa
    <br/> Output: a4
    <br/>
    <br/> String Given: aaabaaaaccaaaaba
    <br/> Output: a3ba4c2a4ba
    <br/>
    <br/> String Given: abcd
    <br/> Output: abcd
    <br/>
  </P>
</div>
<br/>
<p>Your Results:</p>
<div id="results3"></div>
<br/>
<br/>
<br/><br/>
<br/>
<br/>
<br/>
<br/><br/>
<br/>
<br/>
<br/>
<br/><br/>
<br/><br/>
<br/>
<br/><br/>
<br/>
<br/>
<br/>
<br/><br/>
<br/>
<br/>
<br/>
<br/><br/>
<br/>
<br/>
<br/>
<br/><br/>
<br/>

CSS

p {
  padding: 0px 0px 0px 15px;
}

#question {
  border: 1px solid gray;
}

div {
  padding: 15px 15px 15px 15px;
  border: 1px solid blue;
}

JavaScript

//You may use: https://developer.mozilla.org if you need help with syntax
// https://getfirebug.com/firebug-lite-debug.js as external resource for a build-in console window
function Q1(number1, number2) {
  var returnValue = "";
  let i;
	if (number1 < 3) {
  	returnValue += '2,';
    i = 3;
  }
  if (number1 < 4 && number2 > 3) {
  returnValue += '3,';
  }
  if (number1 < 6 && number2 > 5) {
  returnValue += '5,';
  }
  if (number1 < 8 && number2 > 7) {
  	returnValue += '7,';
  }
  i = i || number1;
  
  
  for (; i <= number2; i += 1) {
  	let prime = false;
  	for (let j = 2; j < Math.floor(Math.sqrt(number2)); j += 1) {
    	if (i % j === 0) {
      	prime = true;
      }
    }
    if (!prime) {
    	returnValue += `${i},`;
    }
  }
  
  
  

  return returnValue;
}

function Q2(number1) {
  var returnValue = "";

  //Q2 your code here

  return returnValue;
}

function Q3(string1) {
  var returnValue = "";
	let curr = string1[0];
  let count = 1;
  
  for (let i = 1; i < string1.length; i += 1) {
  	if (curr !== string1[i]) {
    	count === 1 ? returnValue += curr : returnValue += `${curr}${count}`;
    	curr = string1[i];
      count = 1;
    } else {
    	count += 1;
    }
  }
  
  count === 1 ? returnValue += curr : returnValue += `${curr}${count}`;
  return returnValue;
}


$("#results1").append(Q1(1, 100));
$("#results2").append(Q2(808));
$("#results3").append(Q3("aaabbbbaaaaccaaaabba"));
// You may use: https://developer.mozilla.org if you need help with syntax
// https://getfirebug.com/firebug-lite-debug.js as external resource for a build-in console window