Javascript programming every day of the week

Here's one I thought would be simple, which wasn't. The problem is, "return a count of all the vowels (not y) in a string." I thought I'd use regex.exec to capture an array of vowels and find the length of the array... But it only ever returned length 2. I see in the Mozilla Developer Network info page that RexExp.length is 2, but I don't know why I'm getting that here. Can someone troubleshoot?

function VowelCount(str) { 
  var re = /([aeiou])/ig;
  var arr = re.exec(str);
  console.log(arr);
  return arr.length; 
}

console.log(VowelCount('moooo'));

So I pivoted to for loops and came up with this,

function VowelCount(str) { 
  var re = /[aeiou]/i;
  var count = 0;
  for (var i = 0; i < str.length; i++) {
    if (re.test(str.charAt(i))) {
      count += 1;
      console.log(i);
  }
  return count; 
}

This also took some troubleshooting, since the count was wrong when I was using the 'g' flag in the regex. I'm also not sure why that was. Other people I looked at also had mangled looking answers, though of course Matt Larsh has something good,

function VowelCount(str) { 
  var vowels = str.match(/[aeiou]/g);
  return vowels.length;
}

Looks like I need to bone up on str.match.

The next Free Code Camp exercise is to find the length of the longest word in a string (and all of their test strings are free of anything but letters and single spaces). Good points: I had no trouble getting the shape of the solution, and split totally worked great. Actually doing the proper syntax for Reduce required a lot of searching, though, and eventually I basically copied a bit from this webpage about getting comfy with arrays. I should work through that website sometime... Most of the failed reduce trials I don't have copies of, but one that I don't understand is that when I had a 0 in the place I thought was for initial value, right after the anonymous function and before the console.log error-catching readout, here: }, 0);
console.log(foo.length); what I got out of the function was only 0. Baffling. Below is code that works. :)

function findLongestWord(str) {
var words = str.split(' ');
var foo = words.reduce(function(prevWord, thisWord){
if (thisWord.length > prevWord.length) {
return thisWord;
}
else {
return prevWord;
}
});
console.log(foo.length);
return foo.length;
}

findLongestWord('The quick brown fox jumped over the lazy dog');


I feel like I've reversed a string before... I vaguely remember something about halving the length and swapping things around the middle. But this time, when Free Code Camp asked for it as their very first JavaScript coding exercise, I just looped through the entire thing. Woooo!

function reverseString(str) {
var reverseStr = '';
for (var i = str.length - 1; i > -1; i--){
reverseStr += str[i];
console.log(reverseStr);
}
return reverseStr;
}

reverseString('hello');

At first I had just defined the reverseString variable as "var reverseStr;", and the readout I was getting from that console.log in the loop was "NaNo" "NaNol" etc. Second debugging step, when I made the start point of the loop i = str.length - 1 instead of i = str.length, I got "undefinedo" "undefinedol" "undefinedoll" etc. So in the first case it was trying to add the nothing in "hello"[5] to NaN, since why, the sensible programming language thinks, would I be trying to use an addition operator, +, on anything but a number? I'm not sure why trying to add "o" worked; I suppose JavaScript decided that the o it was getting meant that it should be adding to a string or object or some non-number thing, but that string or object or whatever wasn't defined. It's nice that when it failed at adding it relapsed to concatenating.

...I suspect this is a terrible implementation of reversing a string. Any takers?

The Free Code Camp at this point suggests I should be pairing, and a nice guy in the chat room linked me up with a copy of Screenhero (they've joined Slack and are not taking new signups unless someone already inside invites you in), which they suggest is good for being able to remotely cowork and see everything on another screen... Another guy in the chat suggested coderpad.io or another .io solution instead, as less dangerous and better functioning. What do people think, re: screen sharing programs?

I've been through the first few chapters of the Aquent Gymnasium Javascript Foundations course, but that's momentarily on hold due to the Grim Flash Bugs of Hacking Team... Before that, I had some fun learning how to screw around with developer tools: F12 toggles the modern update of "view source", where you can look if webpages you visit have scripts that log things to the console, look at the scripts and how they're written, interesting stuff like that.

Around the 4th I had the idea that it would be fun to make a program that would show you the layout of the stars on the American flag (the star area is called the "union", apparently) once we added Puerto Rico as a state... And for any number of states, really. My thought was to use the brute-force ability of programs, find every rectangle that contains the right number of stars (like, for 9: 1x9, 4+5, 3x3, 5+4, 9x1) and then compare their proportions to the proportions of the union, and I got all the sub bits working. However, I've gotten hung up on the math, and looping, that breaks the number of stars into possible rectangles. I need something that will return an array of every grouping that adds to the correct number of stars, where the groupings are an even number of rows of length "X" plus any number of rows of length "X-1". (The flag has, in the past, looked like an I-beam).

A friend of mine at Amazon pointed out this online thing for learning to code Javascript, Free Code Camp. The idea is that once you know just enough to be useful, you start being of use by coding actual projects for nonprofits that sign up with them; and then you have a portfolio of work to use to get a job. Sounds pretty great, though today I hit the JQuery section and it popped me over to Codecademy... I did that last year, when it was Code Year ("Learn to code in a year!"), and it's not my style. It takes minutes of cutting and pasting at their direction to be able to shake out a bit of actual information, and they rarely explain the reasons behind anything. I vastly prefer just reading everything at once and having more freedom to build a thing...

But I know much more about CSS, now, so woo!

There I was on Eloquent Javascript's problem 5.4, http://eloquentjavascript.net/05_higher_order.html#h_jr7hZiuR7+

The for loop seemed simple, but what I came up with wasn't processing "isNaN" as a function.

var every = function (array, compare) {
for (var i = 0; i < array.length; i++) {
if (array.i !== compare)
return false;
else return true;
}
};

console.log(every([NaN, NaN, NaN], isNaN));
// → should be true, but was showing as false
console.log(every([NaN, NaN, 4], isNaN));
// → false

Putting the "compare" in the if condition in () parentheses (because I had a memory that some form of parentheses would make javascript try to find the value of a thing... Thinking about this, that was probably a memory from getting values of keys, done with [], which in this case I believe would flag "compare" as an array) didn't fix it. Trying for != to allow for type conversion didn't fix it.

I looked at the hints, and they didn't talk about making functions do their thing; they talked about setting up the loop like "forEach". I took an abortive stab at redoing the loop to use forEach... This didn't run, and the linter in JSBin was sad about my use of break. (I'm still not sure what's up with break.)

function every (array) {
array.forEach(function(compare) {
if (array !== compare) {
break;
}
else return true;
});
return false;
}

I tabbed over to the annotated book: https://docs.google.com/document/d/1aa2-HtUglQrAps31s4LdTPVsiFb1BxhyjZolxeezzcI/edit?_escaped_fragment_=#!

Predicate functions were never defined in the book so I’ll quickly explain them here.

A predicate function is a function that returns true or false based on some condition. In this problem, we’re using isNaN(testValue), which returns true if testValue is NaN (remember this means not a number), and false otherwise.

Huh. At first that seemed a bit unfair, a new unexplained type of function. But then, a closer reading would have indicated that the compare thing had to be a function; and I'd even previously went back to the appearance of isNaN in Eloquent Javascript and managed to whizz past the part where it was summoned into action like so, isNan("some thing").

The working answer,
var every = function (array, compare) {
for (var i = 0; i < array.length; i++) {
if (!compare(array[i]))
return false;
}
return true;
};

And "some" is trivial from there.