Mock Technical Interview – Javascript Developer Entry Level
Preparing for a technical interview can be nerve-wracking, especially for an entry-level position as a Javascript developer. However, with the right mindset and preparation, you can confidently showcase your skills and secure the job. In this article, we will discuss some common topics and questions that you may encounter in a mock technical interview as a Javascript developer at the entry-level.
Understanding Basic Concepts
Before diving into more complex questions, interviewers often want to assess your fundamental knowledge of Javascript. You may be asked questions about the difference between var, let, and const, or how closures work in Javascript. Make sure you have a clear understanding of concepts like data types, scope, and hoisting.
Example Interview Question:
“What is the difference between ‘null’ and ‘undefined’ in Javascript?”
To answer this question, you can explain that both ‘null’ and ‘undefined’ represent the absence of a value, but they are used in different contexts. ‘Undefined’ is the default value of a variable that has been declared but has not been assigned a value. On the other hand, ‘null’ is a value that represents intentional absence or nonexistence.
Working with Objects and Arrays
Javascript heavily relies on objects and arrays for data manipulation. Hence, it is important to have a good understanding of how to create, access, and modify data in objects and arrays. Interviewers often ask questions about object prototypes, inheritance, or array manipulation using built-in methods like map, filter, and reduce.
Example Interview Question:
“How can you check if a specific key exists in an object in Javascript?”
To answer this question, you can mention the ‘hasOwnProperty’ method, which allows you to check if a specific key exists in an object. Alternatively, you can use the ‘in’ operator to check if a key exists anywhere in the prototype chain.
Understanding Asynchronous Operations
Javascript is known for its asynchronous nature, and it is crucial for developers to understand how to handle asynchronous operations effectively. You may be asked questions about callbacks, promises, or async/await syntax.
Example Interview Question:
“What is the difference between callbacks and promises in Javascript?”
In your answer, you can explain that callbacks are a way to handle asynchronous operations by passing a function as an argument to another function, which will be called once the operation is complete. Promises, on the other hand, are objects that represent the eventual completion or failure of an asynchronous operation and allow for more readable and manageable code flow.
Problem-Solving and Algorithmic Questions
Interviewers may also test your problem-solving skills by asking algorithmic questions or providing coding challenges. These questions are designed to assess your problem-solving approach, efficiency, and ability to write clean and optimized code.
Example Interview Question:
“Write a function in Javascript to find and return the first non-repeated character in a string.”
To solve this problem, you can iterate over each character in the string and store the count of each character in an object. Finally, iterate over the object to find the first character with a count of 1.
function findFirstNonRepeatedChar(str) {
const charCount = {};
for (let char of str) {
charCount[char] = (charCount[char] || 0) + 1;
}
for (let char of str) {
if (charCount[char] === 1) {
return char;
}
}
return null;
}
console.log(findFirstNonRepeatedChar("javascript")); // Output: 'j'
Conclusion
Preparing for a technical interview as a Javascript developer at an entry-level position requires a strong foundation in the language’s core concepts, familiarity with object-oriented programming, and an understanding of asynchronous operations. By studying and practicing these topics, you can increase your chances of success in a mock technical interview, impress the interviewer, and land your dream job.
This is great! Props to Eli for pushing past the nervousness and settling in, it must've been extra hard for him knowing it was going to be recorded and uploaded to YT. I would LOVE more of these! I'd also love to volunteer to do a mock interview with you (me as the interviewee), if you'd like. I might not be quite at the point I'd need to be YET but I'd still love to do it!
good job , the last solution still has a bug the final answer is <div></div><p>hello</p></div></div> which is not right
too much relatable
00:08 Learning programming has been frustrating due to personal traits but still excited about big projects.
05:06 An array in JavaScript is used to organize data, while an object is used when we want to associate named keys with values.
16:35 Write a function to capitalize every other letter in a string
21:38 Loop through the string and capitalize every other character.
32:21 There was a bug in the code that caused an extra letter to be added in the output.
37:50 The purpose of the function is to correct the closing tags for div elements in an HTML string.
48:02 There is a need to find a specific sequence of characters in a given text.
53:21 To solve the problem, use an array and loop through the characters
1:04:24 Keep track of the number of div tags found.
1:10:08 Build the entire string by adding characters one at a time.
1:20:25 Fixing bugs and iterating over strings
1:26:03 Successfully completed a complex coding interview question
1:34:54 Applying for positions will benefit from watching this process
Crafted by Merlin AI.
const f = (s) => {
let arr = s.split('');
const res = [];
let isDivPassed = false;
for (let i = 0; i <= s.length; i++) {
if (s.slice(i, i + 5) === "<div>") {
if (isDivPassed) {
res.push("</div>");
i += 5;
isDivPassed = false;
} else {
res.push(s[i]);
isDivPassed = true;
}
} else res.push(s[i]);
}
return res.join('');
second question without edge cases : str.replace(/<div>w+/gi,val=>val+'</div>')
is the interviewer also a junior?
sir i am a beginner, i tried to solve the second one by myself, so can you please provide me feedback and also suggestions if possible.
function closeDiv(html) {
let splitedHtml = html.split("<div>");
let closedDivArray = [];
let element = "";
for (let i = 0; i < splitedHtml.length; i++) {
element = splitedHtml[i];
if (i % 2 !== 0) {
closedDivArray.push(`<div>${element}</div>`);
} else {
closedDivArray.push(element);
}
}
console.log(closedDivArray.join(""));
}
closeDiv(
"<div><p>this is a<div>paragraph</p><div><p>this is a new <div>paragraph</p><div>another div<div>"
);
Amazing video and great job Eli!
This was an amazing video to sit down and watch being a beginner learner into coding myself. Watching this whole video gave me a lot tips on how to tackle problems and how to go through it step by step to get a better understanding of the question given. By questioning/answering edge cases and giving examples of what you want the program to actually run/spit out. I, myself, never really went through this process and just went straight into the coding aspect and try work my way through that which made it really hard on me, decreasing my confidence.
I give huge props to Eli because he came into this mock interview not prepared at all. You can tell Eli was nervous by the way he laughs and how he moving around a lot and wasn't really still at first. But after seeing you giving him the guidance and patiently talking to him through the process, Eli became more a lot confident and was able to work solving the code faster by understanding it.
The first coding problem was was done beautifully and I was able to understand it every step of the way. But the second coding question became a lot hard to follow due to the second if statement and understanding where to put each variable within the various brackets. My brain would always explode when I see more than 20 lines of code and would constantly have to run myself through the code repeatedly to understand it again.
Also, I really enjoyed on how Nader kept a calm/cheerful mood when talking to Eli even after seeing his nervousness when working through the problems by giving him reassurance on how he can approach things whenever Eli was stuck. I feel like I, myself, would have a better understanding If I had someone I can talk to and ask a lot of questions if I ever get stuck on how to approach things or ask how certain code works.
UwU
here's the solution i came up with for the second problem:
function closeDivs(html) {
// start by finding all the locations of <div> tag in the string
const divIndices = [];
let index = -1;
do {
index = html.indexOf('<div>', index+1);
if(index !== -1) {
divIndices.push(index);
}
} while(index !== -1);
// now we can interate over all our indicies of <div>,and insert '/' for every second div
let arr = Array.from(html);
let indexOffset = 0; // splice will modify array, every time we do this we need to insert the next one space further
for(let i=0; i<divIndices.length; i++) {
if(i%2 === 1) {
arr.splice(divIndices[i]+1+indexOffset,0,'/');
indexOffset += 1;
}
}
return arr.join('');
}
hi.
hahah.
he is old and he is 26. What about me and I am 45 and just started learning.
Love this content. Gives us aspiring developers an idea of what to expect in a real interview!
Wow! So helpful! Thanks
If the questions were like this in the current market interviews, I would have smashed them like coconuts
I like how the interviewer is supportive
function closeDiv(html) {
let correctedStringHTML = "";
let yesFounded = false;
for(let i = 0; i < html.length; i++){
if(yesFounded){
if(`<${html[i + 1]}${html[i + 2]}${html[i + 3]}>` === "<div>"){
correctedStringHTML += "</div>";
yesFounded = false;
i = i + 4;
continue;
}
}
if(html[i] === "<"){
if(`<${html[i + 1]}${html[i + 2]}${html[i + 3]}>` === "<div>"){
yesFounded = true;
correctedStringHTML += "<div>";
i = i + 4;
}else{
correctedStringHTML += html[i];
}
}else{
correctedStringHTML += html[i];
}
};
return correctedStringHTML;
}
closeDiv('<div><p>hello there<div></p><div><div><p>hello<i><div></i><div>');
in just five minutes
No one is talking about how Nader has manly deep sweet voie
if opening and closing tag are correct normaly the code let some thing correct !!
it seeems you consontrate oly an the second ones…
tell me if im wrong..THANKS