javascript - array does not get set back to [] (blank) - javascript

I have this code and every time that the first for loop starts again I want it to reset the array to blank as it is using a new user, but I get an out put with all the values in one array.
var items = [];
for (var i = 0; i < userArray.length; i++) {
items.length = 0;
for (var i2 = 0; i2 < test.length; i2++) {
var UserFavourite = Parse.Object.extend("UserFavourite");
var queryUserFav = new Parse.Query(UserFavourite);
queryUserFav.equalTo('item', test[i2].get('item'));
queryUserFav.equalTo('school', test[i2].get('school'));
queryUserFav.equalTo('user1', userArray[i])
queryUserFav.find().then(function(res) {
for (var i3 = 0; i3 < res.length; i3++){
var item = res[i3];
var itemName = item.get('item');
items.push(itemName);
if (items !== []) {
console.log(items.toString()+" + ")
}
}
});
}
}
userArray.length is equal to 2 and test.length is equal to 20. If you were wondering. And when it get to the first for loop I want the array to be set back to blank but it isn't?
Thanks for the help in advance.

I thnk you should use set this:
items.length = 0
because items = []
creates a new array which is not the same.
Also add some promises to make the async requests wait

Have you tried:
items.length = 0;
instead of:
items = [];

Can you please concatenate a "+" to the items variable in console log, like so:
console.log(items.toString()+" + ");
Just for debugging purposes to see if the array is actually being cleared or not. I believe it already might be cleared.

Your issue is that you're executing a loop and triggering async code.
Your loop will completely finish before the first bit of async code is executed:
i == 0
reset items
loop over test (20 items)
queue up a find() with async success handler
i == 1
reset items
loop over test (20 items)
queue up a find() with async success handler
... some time later when find() calls finish ...
call each async block using the items array
Unless there's some other code you're not showing that needs to access the items array, just create it inside your success handler instead:
queryUserFav.find().then(function(res) {
// create array here:
var items = [];
for (var i3 = 0; i3 < res.length; i3++){
var item = res[i3];
var itemName = item.get('item');
items.push(itemName);
if (items !== []) {
console.log(items.toString()+" + ")
}
}
});

Related

FOR loop and Array issue

I'm using Adobe Livecycle Designer ES4 to create some report. Based on XML a try to fill table. I have problem with Array. I push data into array in for loop. Below examples of my code:
Results - blank textbox
var print_data = xfa.record.containerPrintingData;
var sfcArray = [];
for (var i = 0; i < 10; i++) {
sfc = print_data.resolveNode("sfcPrintingData["+ i +"]").sfc.value;
sfcArray.push(sfc);
};
this.rawValue = sfcArray.toString();
Results - get all items
var print_data = xfa.record.containerPrintingData;
var sfcArray = [];
for (var i = 0; i < 10; i++) {
sfc = print_data.resolveNode("sfcPrintingData["+ i +"]").sfc.value;
sfcArray.push(sfc);
this.rawValue = sfcArray.toString();
}
Results - get 2nd item x 10
var print_data = xfa.record.containerPrintingData;
var sfcArray = [];
for (var i = 0; i < 10; i++) {
sfc = print_data.resolveNode("sfcPrintingData[1]").sfc.value;
sfcArray.push(sfc);
this.rawValue = sfcArray.toString();
}
Why 1st example don't work and 2nd work correct? I need use this array in another loops. How to solve it?
Because, If it has 2 items, and you looping it for 10.
What happends is, when this.rawValue = sfcArray.toString(); is inside the loop, this.rawValue gets updated 2 times. First time One item will be there. second time 2 items.
For the next iteration there is no 3rd item. So code breaks with error. But this.rawValue still have 2 items.
Where as, when this.rawValue = sfcArray.toString(); is outside the loop, the code breaks with error and this.rawValue don't have any items in it.

Pass array values to another array

I have an array of input fields called '$inputFieldsArray' then I slice them to group by 3 into 'newArray' then I need new array value for each item to assign to another array cause in the end I need an array with input fields values grouped by 3. The end goal is to get an array which contains for 9 input fields ex [[i1,i2,i3],[i4,i5,i6],[i7,i8,i9]].
For some reason 'stringArray' output is nothing, first two arrays print correct results. It's probably some mistake I do regarding JS arrays.. Sorry js is not my main language, I try to learn it. Thanks.
Here is a screenshoot with chrome console:
Here is my function:
$($submitButton).click(function () {
// Get number of input fields
let $total = $("input[name^='bodyHeader']").length;
// Get input fields as objects
let $inputFieldsArray = $("input[name^='bodyHeader']");
let newArray = [];
let stringArray = [];
let j = 0;
// Group input fields by 3
for (let i = 0; i < $total - 1; i += 3) {
newArray[j] = $inputFieldsArray.slice(i, i + 3);
j++;
}
// Extract string values from newArray and pass them into stringArray
for (let k = 0; k < newArray.length - 1; k++) {
stringArray[k][0] = newArray[k][0].value;
stringArray[k][1] = newArray[k][1].value;
stringArray[k][2] = newArray[k][2].value;
}
// Print to test results
console.log($inputFieldsArray);
console.log(newArray);
console.log("String Array: " + stringArray);
... // Function logic is not complete
});
SOLUTION:
There is no way to declare dynamic length bidimensional array in js. Use this approach suggested by #Stephan :
stringArray[k] = [newArray[k][0].value, newArray[k][1].value,
newArray[k[2].value];
or this approach suggested by #Lorenzo Gangi:
var matrix = [],
cols = 3;
//init the grid matrix
for ( var i = 0; i < cols; i++ ) {
matrix[i] = [];
}
stringArray[k] is undefined because you defined stringArray as [] (Your browser probably threw an exception). Additionally newArray[k] starts at index 0.
You could write stringArray[k] = [newArray[k][0].value, newArray[k][1].value, newArray[k][2].value] instead.
Basically,
stringArray[k]
is undefined yet, therefore setting its [0] property wont work. May do:
stringArray[k] =newArray[k].map(el=>el.value);
Alltogether:
$($submitButton).click(function () {
let stringArray = $("input[name^='bodyHeader']").toArray().reduce((res,_,i,arr)=>((i%3==0 && res.push(arr.slice(i,i+3).map(e=>e.value))),res),[]);
});

shift changes the length of the array so the last element is not going to be executed

In JavaScript, for a array, if methods such as pop, shift is used, the length of array changes as well. In my JS code below, it never executes the third elements 'Ds3' in the array since after the notes.shift() is executed, the length of the array becomes 0 so it just jumps out of the for loop, I do not know how to change the code so it can actually execute the 'Ds3'. Hope someone could help me out. Thank you in advance.
Code 1:
$(document).ready(function() {
var notes = ['F2', 'As2','Ds3'];
for(i = 0; i < notes.length; i++) {
$('#_' + notes.shift()).addClass('just_do_it');
alert(notes.length);
}
});
For code 2, I do not know why when I sort of make the one line code to two liner, the code does not work at all. Thank you in advance.
code 2:
$(document).ready(function() {
var notes = ['F2', 'As2','Ds3'];
var count = 0;
for(i = 0; i < notes.length; i++) {
var note = notes.shift();
$('#_' + note).addClass('just_do_it');
count++;
alert(notes.length);
}
});
Is there a reason why you want to empty that array? If insist on it, try changing to a while loop.
var notes = ['F2', 'As2','Ds3'];
var count = 0;
while(notes.length > 0){
var note = notes.shift();
$('#_' + note).addClass('shown');
count++;
alert(notes.length);
}
If I may add, you're also incrementing the count as you loop through the array. Rather you can get the count immediately just by getting the length of the array like this var count = notes.length
Also since you mentioned pop and shift arrays methods, you should checkout other array methods such as forEach, map or reduce
Since shift() is indeed destructive you could simply use the index of that iteration in the loop and leave the array unaltered
for(i = 0; i < notes.length; i++) {
// switch from `notes.shift() to notes[i]
$('#_' + notes[i]).addClass('just_do_it');
count++;
alert(notes.length);// length remains unchanged
}
Or using join() to create a selector for all and not use any loop
$('#_' + notes.join(',#_') ).addClass('just_do_it');
You could also try:
for (var count = notes.length; count > 0; count--) {
$('#_' + notes.shift()).addClass('just_do_it');
}
or
while (notes.length > 0) {
$('#_' + notes.shift()).addClass('just_do_it');
}

Splice NOT removing certain characters

I'm working on some codewars problems and I came to this 'remove noise thing', I guess the point is to escape backslash \ and use replace method, which was easy. But I didn't want to use replace, instead I found myself in trouble trying to remove items with splice method.
Funny thing is, when I debug in Chrome dev tools, step by step I see items get removed, but console.log spits out certain characters($/·|ªl) problematic to remove, and at the end gets returned and join with those characters. Why is that?
function removeNoise(str) {
var base = "%$&/#·#|º\ª";
var arr = str.split('');
for(var i = 0; i < arr.length; i++) {
var item = arr[i];
var condition = base.indexOf(item);
if(condition + 1) {
//works like a charm
//arr[i] = '';
arr.splice(i,1);
//this thing wont work
//when debugging it removes the items from the array
//console log print no removing
}
}
return arr.join('');
}
removeNoise('he%$&/#·#|º\ª\llo'); //=> $/·|ªllo
You're using splice to remove entries from your array, but you're then incrementing i for the next loop. If you remove the entry at index 5 from a 10-entry array, what was the entry at index 6 is now at index 5 (of what's now a 9-entry array), so you don't want to increment your index.
The solution is to use a while loop and only update i if you don't splice:
function removeNoise(str) {
var base = "%$&/#·#|º\ª";
var arr = str.split('');
var i = 0;
while (i < arr.length) {
var item = arr[i];
var condition = base.indexOf(item);
if (condition + 1) {
// Remove this entry, reuse same value for 'i'
arr.splice(i,1);
} else {
// Don't remove this entry, move to next
++i;
}
}
return arr.join('');
}
var result = removeNoise('he%$&/#·#|º\ª\llo');
var pre = document.createElement('pre');
pre.appendChild(
document.createTextNode(result)
);
document.body.appendChild(pre);
You're removing characters from your array. This will throw your indexer variable i out of sync with the characters you want to test. Easy way to fix is to start at the end of the array working your way to the beginning.
Change your for loop to this.
for(var i = arr.length -; i <= 0; i--) {
function removeNoise(str) {
var base = "%$&/#·#|º\ª";
var arr = str.split('');
for(var i = arr.length - 1; i <= 0 ; i--) {
var item = arr[i];
if(base.indexOf(item) >= 0) {
//remove the offending character
arr.splice(i,1);
}
}
return arr.join('');
}
removeNoise('he%$&/#·#|º\ª\llo'); //=> $/·|ªllo

Add two parameters in function into "then" protractor

It is quite clear. I have an array with some links and I want to build a loopto try all of them, but the problem is that link is always 3. It means that it read the last number in my array. Why? How can I fix it?
var categories = ['1','2','3'];
for( var i = 0; i < categories.length; i++ ) {
var link = '/'+categories[i];
browser.get(link);
browser.sleep(2000);
browser.driver.getCurrentUrl().then( function(url) {
expect(url).toMatch(link);
});
}
and I have list of divs and I want to read randomly infos from them. So I made the following
chosenOffer = Math.floor( (Math.random() * count ) + 1);
offer = element.all( by.className('offer')).get( chosenOffer );
But it shows always error message chosenOffer object...
This is a classic closure problem that is described in detail in:
Using protractor with loops
In your case, just let expect() resolve the promise:
var categories = ['1','2','3'];
for (var i = 0; i < categories.length; i++) {
var link = '/' + categories[i];
browser.get(link);
browser.sleep(2000);
expect(browser.driver.getCurrentUrl()).toMatch(link);
}

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