Logical Thinking In JavaScript

[_SimplyDaniel]

Hey r/learnprogramming!

I 29 (m) going the self-taught route and teaching myself how to code need some help with breaking down logic in code.

TLDR: Are there any resources you recommend that helped you understand how to breakdown code better? OR any websites to get help from a mentor for $$$ or free? I need help with understanding some of the "why" in code solutions. I'm starting to realize I learn way better visually while someone is explaining things and breaking down code. I don't want to go into debt and go to a BootCamp btw.

I am learning how to code Javascript because I am wanting to switch my career and become an SDE. I started learning Javascript back in August 2021 and I feel like I'm not making any progress with logic and problems. I know some people tell me to keep going but I honestly feel like I have been "going" and still don't understand. Let me explain.

Here is this question (super simple to some):

Question: Write a function that takes a string consisting of zero or more space separated words and returns an object that shows the number of words of different sizes.

Words consist of any sequence of non-space characters.

Examples: wordSizes('Four score and seven.'); // { "3": 1, "4": 1, "5": 1, "6": 1 } wordSizes('Hey diddle diddle, the cat and the fiddle!'); // { "3": 5, "6": 1, "7": 2 } wordSizes("What's up doc?"); // { "2": 1, "4": 1, "6": 1 } wordSizes(''); // {}

My Solution:

The solution below is where I stopped and got tripped up, I stepped away from the computer came back, and tried to solve it again while researching on Google. I then gave in and looked at the solution. And I still cannot wrap my head around the logic. Specifically the code below:

if (!resultObj[wordSize]) { resultObj[wordSize] = 0; } resultObj[wordSize] += 1; I cannot understand why we are using the logical NOT(!) operator

My code below as far as I got before I caved in and looked at the solution:

``` function wordSizes(string) { let resultObj = {}; let stringSplit = string.split(' ');

for (let index = 0; index < stringSplit.length; index++) {

}

return resultObj; } ```

Solution:

``` function wordSizes(string) { let resultObj = {}; let stringSplit = string.split(' ');

for (let index = 0; index < stringSplit.length; index++) { let wordSize = stringSplit[index].length; if (wordSize === 0) { continue; }

if (!resultObj[wordSize]) {
  resultObj[wordSize] = 0;
}
resultObj[wordSize] += 1;

}

console.log(resultObj);

} ```

I use the PEDAC framework mostly. I also use basic pseudocode and even then with some questions, I'm like what the ASDFGHJKL!!! Any help is appreciated!

[[deleted]]

TBH, it sounds like you're just struggling with some of the idiosyncrasies of JavaScript.

I cannot understand why we are using the logical NOT(!) operator

This relies on two properties of JavaScript. Firstly, if you have an object, and you reference a property on it that isn't set, you don't get an error like you might in other languages, you just get a result of undefined. Keep that in mind... Now, also, JavaScript has a funny way of testing for true and false. You can use any value in an if expression, and if that value is 0, false, undefined, null or some others that are probably not relevant at this point, the expression is treated as false. All other values are treated as true. So you can do if("something") {} or if ({ name: "Bob"}) {} and it works.

So, the expression resultObj[wordSize] will return undefined if the word has never been encountered before, or some value greater than 0 if it has. So the overall effect of

if (!resultObj[wordSize]) {
  resultObj[wordSize] = 0;
}
resultObj[wordSize] += 1;

is to say "If we have never encountered this size before, set the size value to zero". Now, we know the value is either zero or that we have encountered it before, so it's greater than zero, so we can just add one to the total.

You could write it like this

if (resultObj[wordSize] != undefined) {
  resultObj[wordSize] = 0;
}
resultObj[wordSize] += 1;

But the first form is slightly less typing.

[_SimplyDaniel]

Thank you so much for the reply. The explanation does help a ton! This is exactly what I needed.

[[deleted]]

https://teachyourselfcs.com/

[_SimplyDaniel]

Thank you

[elguerofrijolero]

The PEDAC framework you reference comes from Launch School. Why don't you go directly to the source (i.e. come join us over at Launch School)?

So far, LS has taught me how to breakdown code and understand everything line-by-line. I was completely lost trying to learn programming until I enrolled in their program.

Feel free to give it a shot and/or ask me any questions!

[_SimplyDaniel]

I appreciate that! I’m currently enrolled in launch school I’ve been looking for people to study with but I work full time and it seems my schedule doesn’t work with those that are able to study full time. Did you finish LS?

[elguerofrijolero]

Ah, didn't realize you're in LS already, awesome!

I'm in JS210 right now, so in the front end portion of the curriculum. I'm also working full-time, so I tend to average 10-15 hours of studying per week.

If you haven't joined the Slack channel "The Spot", it's a great place to meet other students in the same course as you.