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javascript - if else not resulting in expected comparision [closed]

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I am new to javascript. I am having a little issue here.
Is javascript if / else statement different than other languages (c++, java, python)?
Here is the issue that I am having.
if else statement only accepts i == 0 and i == 1 into my new array from myArray.
Why am I not be able to separate other elements into my new array? I used myArray for an example. In my real problem, I wouldn't know how many elements I have. That is why I have set up variables threetimes and increaseByThree. I am just trying to separate name, zip code, and amount into the different array by using a for loop.
var nameArray = [], zipCodeArray = [], totalAmountArray = [];
var threeTimes = 3;
var increaseByThree = 0;
var myArray = ["Eric ", "94990", "540", "Sam ", "303030", "350"];
for(var i = 0; i < myArray.length; i++) {
threeTimes += 3;
increaseByThree += 3;
if(i == threeTimes || i == 0) {
nameArray.push(myArray[i]);
} else if(i == increaseByThree || i == 1) {
zipCodeArray.push(myArray[i]);
} else {
totalAmountArray.push(myArray[i]);
}
}
console.log(nameArray)
console.log(zipCodeArray)
console.log(totalAmountArray)

Assuming your array will be in the format [a0, b0, c0, ....., aN, bN, cN] where N is the number of 'entries' - 1; you could simplify your logic that you determine where to put the value by:
const myArray = ["Eric ", "94990", "540", "Sam ", "303030", "350"];
const nameArray = [], zipCodeArray = [], totalAmountArray = [];
for(var i = 0; i < myArray.length; i++) {
switch (i % 3) {
case 0:
nameArray.push(myArray[i]);
break;
case 1:
zipCodeArray.push(myArray[i]);
break;
case 2:
totalAmountArray.push(myArray[i]);
break;
}
}
console.log(nameArray)
console.log(zipCodeArray)
console.log(totalAmountArray)
This will work for any size array and cuts out the need for the unnecessary variables and if-else blocks. Here is a helpful link for javascript's switch block
(https://www.w3schools.com/js/js_switch.asp) which are much cleaner as opposed to if-else blocks and show the intent more clearly in this case.

Create element unique id with addEventListener (not jquery) [closed]

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I have this:
var divProducthere= document.getElementById('divProducthere'); //div
var productbutton = document.getElementById('productbutton'); // button
productbutton.addEventListener('click',prodElement);
function prodElement(){
for (var i = 0; i < 9; i++) {
var selectProduct = document.createElement('select');
selectProduct.id = 'r'+i;
divProducthere.appendChild(selectProduct);
}
this does not work for me, because I just need to create the elements with the click event, one by one, but assigning unique id to each of the created elements

Put the counter in a global variable.
var select_counter = 0;
function prodElement() {
select_counter++;
var selectProduct = document.createElement('select');
selectProduct.id = 'r'+select_counter;
divProducthere.appendChild(selectProduct);
}

You can create a unique id like this:
function uniqId(length = 6) {
return (Math.random().toString(36) + Math.random().toString(36)).substr(2, length);
}
for (let i = 0; i < 10; i++) {
console.log(uniqId(parseInt(Math.max(2, Math.random() * 10))))
}

insert a string at a specific position [closed]

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i have an array and i want to insert "ZZ" if the current array value(string) contains "ata", the code should replace at the end of "ata" word.
var duplicatesArray = ["abıca","abrık","apşak","abbak","abu","aparma","apalisına","appak","aparmadutı","apşak","apışık","apşak","apışıklık","apışık","apalak","apılamak","apul","apul","apulamak","aparmak","at","arkasına","gelmek","ata","atabeg","at","eri","at","ağaç","at","oğlanı","at","akdarıcı","at","otayıcı","at","uşağı","at","oğlanı","at","oynağı","at","bırakmak","at","boynuna","düşmek","at","boynuna","düşmek","at","cıvlandurmak","at","çapmak","at","çapmak","at","depretmek","at","depmek","atı","doldurmak","at","segirtmek","ateş","evi","ateş","göyniigi","atışmak","ateşe","urmak","ateşe","nal","komak","at","şalmak","at","şalmak","at","tonı","at","kaşnısı","at","kaldırmak","at","kulağı","at","koparmals","at","koşmak","at","kulağı","götliği","atlaz","atlandurmak","atlandurmak","atlanmak","atlu","azuğı","atımı","yir","ata","atalar","atıcıduğı","aç","itmek","acıtğan","acıtmak","aç","dirilmek","acır","acırak","acışıklık","acışmak","aç","tutmak"
];
var uniqueArray = duplicatesArray.filter(function(elem, pos) {
return duplicatesArray.indexOf(elem) == pos;
});
for (var i = 0; i < uniqueArray.length; i++) {
var st = uniqueArray[i];
if((st.endsWith("mak")==false) && (st.endsWith("mek")== false) && (st.length>3))
{
var b = "ata";
var insert = "ZZ";
var position = st.indexOf("b");
st = st.slice(0, position) + insert + st.slice(position);
document.writeln(st);
document.write("<br>");
}
}

I may need to edit this answer later once some details have been clarified, but it seems like you should use the .map() method on your uniqueArray.
This code will walk through each word in the list and either let it unchanged or apply the replacement if all conditions are fulfilled.
// using a shorter, already deduplicated list for sake of clarity
var uniqueArray = [
"abıca","gelmek","ata","atabeg","at","eri","yir","atalar","tutmak"
];
var result = uniqueArray.map(function(word) {
return (
!word.endsWith("mak") &&
!word.endsWith("mek") &&
word.length > 3 ?
word.replace(/ata/, "ataZZ") : word
);
});
console.log(result);

I am right or wrong? :)
var initialArray = ["abıca","abrık","apşak","abbak","abu","aparma","apalisına","appak","aparmadutı","apşak","apışık","apşak","apışıklık","apışık","apalak","apılamak","apul","apul","apulamak","aparmak","at","arkasına","gelmek","ata","atabeg","at","eri","at","ağaç","at","oğlanı","at","akdarıcı","at","otayıcı","at","uşağı","at","oğlanı","at","oynağı","at","bırakmak","at","boynuna","düşmek","at","boynuna","düşmek","at","cıvlandurmak","at","çapmak","at","çapmak","at","depretmek","at","depmek","atı","doldurmak","at","segirtmek","ateş","evi","ateş","göyniigi","atışmak","ateşe","urmak","ateşe","nal","komak","at","şalmak","at","şalmak","at","tonı","at","kaşnısı","at","kaldırmak","at","kulağı","at","koparmals","at","koşmak","at","kulağı","götliği","atlaz","atlandurmak","atlandurmak","atlanmak","atlu","azuğı","atımı","yir","ata","atalar","atıcıduğı","aç","itmek","acıtğan","acıtmak","aç","dirilmek","acır","acırak","acışıklık","acışmak","aç","tutmak"];
var newArray = []
var regexp = /(ata)(.*)?/;
for (var i = 0; i< initialArray.length; i += 1) {
newArray.push(initialArray[i].replace(regexp, "$1ZZ$2"))
}
console.log(newArray)
// ... "gelmek", "ataZZ", "ataZZbeg" ...

Elegant method to compare an array of strings to another array of strings [closed]

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Question: How can I elegantly compare an array of strings to another array of strings thus returning an array of non-matching strings
var master = ['1','2','3','4']
var versioned = ['1a','2','3b','4']
var errorLog = []
var count = 0;
//this for loop doesn't work :(
for(var i = 0; i < versioned.length - 1; ++i ){
for(var j = 0; j < master.length -1; ++j){
if(versioned[i] === master[j]){
console.log('cleared');
}
if(count === master.length){
errorLog.push(versioned[i]);
}
}
}
loop will return ['1a', '3b'];
I feel like filter() or map() or reduce() will do this but I'm unable to wrap my brain around this properly.

var master = ['1','2','3','4'];
var versioned = ['1a','2','3b','4'];
function diff(needle, haystack){
return needle.filter(function(item){
return !~haystack.indexOf(item);
});
}
console.log(diff(versioned, master)); //["1a", "3b"];
~ NOTing any number equals -(x + 1). so ~-1 becomes 0, which is the only falsy.
~master.indexOf(item) is the same as master.indexOf(item) !== -1

Improving performance while iterating two nested loops [closed]

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I calculate a "Top-5-List" of Birthplaces organized in an array of objects in this form
var myObjArr =[
{
"birth":
{
"year": 2012,
"name": "Manchester, Vermont, USA",
}
} , (and so on)
];
My approach however does not seem to be much performant:
for (var i = 0; i < myObjArr.length; i++) {
var alreadyListed = -1;
for (var j = 0; j < resultData.length; j++) {
if(resultData[j].key == myObjArr[i]['birth']['name']) { // birthname already in resultData
alreadyListed = j;
break;
}
}
if(alreadyListed != -1 ) { // birthname already in resultData -> raise count
resultData[alreadyListed].count += 1;
}else { // birthname not yet in resultData -> add to resultData
resultData.push({key: myObjArr[i]['birth']['name'], count: 1 });
}
}
}
Neiter javascript's forEach nor angulars angular.forEach seem to improve the performance. Any Suggestions?

You can use an object as a dictionary instead of using an array and looking for a key by iterating, this way the second "loop" is done by the Javascript implementation when looking for object keys (also it's probably not a linear scan but an hash table lookup):
var result = {};
myObjArr.forEach(function(obj) {
var key = "!" + obj.birth.name;
result[key] = 1 + (result[key] || 0);
});
I'm always adding a "!" in front of the key when using objects as dictionaries because all Javascript objects do have an inherited constructor property and I don't want to interfer with that.
The (x || 0) trick is to start with a 0 when a name has not seen before (undefined is falsy in Javascript). Adding 1 to undefined instead results in NaN.
If you really need an array as result the code is only slightly more complex:
var result = [];
var index = {};
myObjArr.forEach(function(obj) {
var key = "!" + obj.birth.name;
var ix = index[key];
if (ix === undefined) {
// Allocate a new entry
index[key] = result.length;
result.push({key:key, count:1});
} else {
result[ix].count += 1;
}
});