abhishekdata / lead-analyst-test

Lead Web Analyst Competency Test

Lead Web Analyst Competency Test

Instructions

• Please use native JavaScript and not jQuery or similar libs
• Please send us the test results in a text file
• Bonus points if you use Github or Bitbucket to version control you test results

We suppose this test require from 3 to 4 hours. Thanks in advance for your time spent on this test!

Task 1. Floats.

• Please explain why this code console.log(0.1 + 0.2 == 0.3); outputs false in console?
• Please suggest fix to make this expression working as expected.

Task 2. Sum function.

• Write a sum function which will work properly when invoked using syntax below:

console.log(sum(2,3)); // Outputs 5 

Task 3. Loops.

Consider you have code snippet like this:

for (var i = 0; i < 5; i++) {
  var btn = document.createElement('button');
  btn.appendChild(document.createTextNode('Button ' + i));
  btn.addEventListener('click', function(){ console.log(i); });
  document.body.appendChild(btn);
}

• What will be the output when user clicks on Button 1 and why?
• Please, suggest a fix to get the expected behavior.

Task 4. Extracts all query strings from URL

Write a JavaScript function which extracts all query strings from URL and push them into a JavaScript object named as 'datalayer' as key values.

Example URL:

http://www.datalicious.com/?pia.ca=72208039&pie.de=[e-mail]&pin.gn=Christian&pin.fn=Bartens&pip.de=&oi.na=&ps.na=&pl.ci=&pl.re=&pl.co=&utm_source=purl&utm_medium=purl&utm_campaign=purl

Task 5. Data layer Object

Write a JavaScript function which takes 'datalayer' object from task 4 and convert them in image tag as demonstrated below and append as child to 'body' tag.

<img src="https://example.com/datacollector?pia.ca=72208039&pie.de=[e-mail]&pin.gn=Christian&pin.fn=Bartens">

Task 6. Store and retrieve the data layer

Write a JavaScript function to store and retrieve the 'datalayer' object from task-4 HTML5 storage.

Task 7. Native JavaScript functions

Can you write down any native JavaScript functions that work in Chrome/Firefox and don't work in Internet Explorer or visa-versa?