Develop Reference

How do i split up an array that holds an array?

Hello my fellow JS friends,
I am letting a user import a csv file (excel sheet) and i convert that into
an array. which has 472 rows and 87 columns in this case.
so my array looks like this:
and everything is separated by commas like a usual array.
The issue is I need to separate the array within the array and when i do that i get an array with the length of 9 million, which i think is wrong
vm.allTextLines = files.split(/\r\n|\n/);
var headers = vm.allTextLines[0].split(',');
vm.columnCount = headers.length;
vm.rowCount = vm.allTextLines.length - 1;
for (var i = 0; i < vm.allTextLines.length; i++) {
// split content based on comma
var data = vm.allTextLines[i].split(',');
if (data.length == headers.length) {
var tarr = [];
for (var j = 0; j < headers.length; j++) {
tarr.push(data[j]);
}
vm.lines.push(tarr);
}
}
//this is where i split the array that contains the csv
//data and put it into its own array I believe this is
//where the issue is.
for(var i=1;i<vm.allTextLines.length; i++){
vm.uniqueAll.push(vm.allTextLines[i].split(','));
for(var j=0; j < vm.uniqueAll.length; j++){
for(var r =0; r < vm.uniqueAll[j].length; r++){
vm.arrayOfValuesOfFile.push(vm.uniqueAll[j][r]);
}
}
}
If you can help me correct this for each I would appreciate it alot.
Thank you in advance guys!

I agree with you about the place of error, because it seems you nested the loop in a wrong way. Following a snippet where you can check what I mean.
i.e:
let vm = {
allTextLines:['h1,h2,h3','row1val1,row1val2,row1val3', 'row2val1,row2val2,row2val3'],
uniqueAll: [],
arrayOfValuesOfFile:[]
}
// Here you should not nest the loop
for(var i=1;i<vm.allTextLines.length; i++){
vm.uniqueAll.push(vm.allTextLines[i].split(','));
}
for(var j=0; j < vm.uniqueAll.length; j++){
for(var r =0; r < vm.uniqueAll[j].length; r++){
vm.arrayOfValuesOfFile.push(vm.uniqueAll[j][r]);
}
}
console.log('allTextLines', vm.allTextLines);
console.log('uniqueAll', vm.uniqueAll);
console.log('arrayOfValuesOfFile', vm.arrayOfValuesOfFile);
Of Course you could easily optimize the algorithm:
let vm = {
allTextLines:['h1,h2,h3','row1val1,row1val2,row1val3', 'row2val1,row2val2,row2val3'],
uniqueAll: [],
arrayOfValuesOfFile:[]
}
for(var i=1;i<vm.allTextLines.length; i++){
let currentLinesValue = vm.allTextLines[i].split(',');
vm.uniqueAll.push(currentLinesValue);
for(var r =0; r < currentLinesValue.length; r++){
vm.arrayOfValuesOfFile.push(currentLinesValue[r]);
}
}
console.log('allTextLines', vm.allTextLines);
console.log('uniqueAll', vm.uniqueAll);
console.log('arrayOfValuesOfFile', vm.arrayOfValuesOfFile);

First you should transform you bidimensional array into a one-dimension array.
var allTogether = []; // Array with all your CSV (no matter from which file it came from)
for (var i = 0; vm.allTextLines.length; i++) {
allTogether.push(vm.allTextLines[i]); // Gets the CSV line an adds to a one-dimension array
}
// Now you can iterate over the one-dimension array
for (var i = 0; allTogether.length; i++) {
var csvFields = allTogether[i].split(',');
// Here goes your code that works with the CSV fields.
}

Pushing values in a 2-dimensional array in a for loop in Javascript

I have the following situation in Javascript
I want the end result of the nested loop to be the following:
testArray[,[0,0,0,0],[1,1,1,1],[2,2,2,2],[3,3,3,3]]
but push doesn't seem to work nor does splice. I don't want to create any intermediate arrays because row & j are database driven and their values are actually unknown.
var testArray = [[3],[4]]; // or new Array(3,4);
for (var row=0; row< 3; row++)
{
for (var j=0; j< 4; j++)
{
testArray[j,row].push(j); //?
testArray.splice([j,row],0,j); //?
}
}

As is noted in the comments, your code does not initialize the 2-D array that you think it does. You need to create a new array and push it into the top-level array for each "row" that you require. Each sub-array can then be populated in multiple ways - up to you how you access it and "push" into them. I coded up a solution and created a Codepen for it so that you can play around with the code:
http://codepen.io/jose8a/pen/KMabNw?editors=0011
var testArray = [];
for (var row=0; row<= 3; row++)
{
testArray.push([]);
for (var j=0; j< 4; j++)
{
testArray[j, row].push(row); //?
//testArray.splice([j,row],0,j); //?
}
}
console.log(testArray);

I guess you want to push arrays to another array. This will do it.
var testArray = [ ]; //
for (var row=0; row< 3; row++) {
var tempArr = [ ];
for (var j=0; j< 4; j++){
tempArr.push(row);
}
testArray.push(tempArr);
}

There's a "new" approach to get the needed array by using ES6 Array.fill function:
var testArray = [3,4], result = [];
for (var i = 0; i < testArray[1]; i++) {
result.push([].fill.call(new Array(4), i));
}
console.log(JSON.stringify(result)); // [[0,0,0,0],[1,1,1,1],[2,2,2,2],[3,3,3,3]]
Array.prototype.fill()

Find if Array contains a user

I have a parse background job that contains a simple query.each for one class. This class has 2 Arrays field filled with objects.IDs. Inside this query, for every single object, i need to check if the objects.ID of the first Array are contained in the second Array.
Basically in a simple loop:
var j = 0;
for (var j = 0; j < firstArray.length; j++) {
if(firstArray[j] "isContainedIn" secondArray){
// my custom code
}
}
What i can't figure out is the function to use, if exist..Does javascript have a function like that or i need to make a nested loop to achieve my goal?
EDIT: i worked it out using indexOf but the solution proposed by Shqiptar didn't work so here is the one that actually works:
first Array name = usersEligibleToVote
second Array name = usersThatVoted
for (var j = 0; j < usersEligibleToVote.length; j++) {
if(usersThatVoted.indexOf(usersEligibleToVote[j]) === -1){
console.log("user.id "+usersEligibleToVote[j]+" needs to vote");
} else {
console.log("user.id "+usersEligibleToVote[j]+" has voted");
}
}

var j = 0;
for (var j = 0; j < firstArray.length; j++) {
if(firstArray[j].contains(secondArray))
{
// your custom code here
}
}
And then for checking if an object is the same :
var j = 0;
for (var j = 0; j < firstArray.length; j++) {
if(firstArray[j].indexOf(secondArray) != -1)
{
// your custom code here
}
}

I would process it through a simple jQuery and javascript for loop like so:
var arr1;
var arr2;
var i;
for(i = 0; i < arr1.length; i++) {
if ($.inArray(arr1[i], arr2) {
break; //do things here or what not
}
}

How to add array of arrays in javascript

I have a Javascript array with multiple arrays inside. I was trying to loop through the array to return an aggregated array. So far I have done following with no luck:
var a = [[1,2,3],[4,5,56],[2,5,7]];
var x = [];
for ( var i = 0; i < a.length; i++) {
for ( var j = 0; j < a[i].length; j++) {
console.log(a[i][i] = a[i][j]+a[j][i]);
}
}
I am trying to obtain the following result:
console.log(a); // -> [7,12,66]
Any suggestions or pin points where I can look for examples of similar things would be appreciated.

assuming the elements of a has the same length, the following should work
var x=[];
for(var i=0; i<a[0].length; i++){
var s = 0;
for(var j=0; j<a.length; j++){
s += a[j][i];
}
x.push(s);
}

a[0].map(function(b,i){return a.reduce(function(c,d){return c+d[i];},0);})
// [7, 12, 66]

From dc2 to dc1, try this:
var a = [[1,2,3],[4,5,56],[2,5,7]];
var x = [];
for ( var i =0; i < a.length; i++){
for ( var j = 0; j < a[i].length; j++){
x[j] = x[j] || 0;
x[j] = x[j] + a[i][j];
}
}
This worked in testing, and doesn't error with different array lengths.

How to loop through Nested Json Array with (JavaScript) for loop and display the text

This may be a fairly simple question but it's just not working for me no matter how many times I change the for loop around. So how would you loop through this array using a for loop in JavaScript?
var fielditems =[
[["News Tips"],["Opinions"],["MedMinutes"]],
[["Yes"],["No"],["Maybe"]],
[["How"],["Why"],["When"]]
];
This is what I have and it's not working. I used an alert to just test out the result but it's not even returning anything.
for(itemSet in fielditems){
var itemSetValues = fielditems[itemSet];
for(set in itemSetValues){
var itemValue = itemSetValues[set];
for(value in itemvalue){
alert(itemValue[value]);
}
}
}
What am I doing wrong?

Don't use for() with in for arrays. It's for object properties. Use the standard format instead.
Demo: http://jsfiddle.net/ThinkingStiff/EVWch/
Script:
var fielditems =[
[["News Tips"],["Opinions"],["MedMinutes"]],
[["Yes"],["No"],["Maybe"]],
[["How"],["Why"],["When"]]
];
for( var itemIndex = 0; itemIndex < fielditems.length; itemIndex++ ){
var itemSetValues = fielditems[itemIndex];
for(var setIndex = 0; setIndex < itemSetValues.length; setIndex++ ){
var itemValue = itemSetValues[setIndex];
for(var valueIndex = 0; valueIndex < itemValue.length; valueIndex++ ){
alert(itemValue[valueIndex]);
};
};
};
​

Firstly, console is your friend. You get error ReferenceError: itemvalue is not defined because javascript is case sensitive. Change itemvalue in the most nested loop to itemValue.
Secondly, if you want iterate thorugh an array, you should use for-loop instead for-in-loop

Don't use for-in loops on arrays
Don't use (running) variables without declaring them as local
for (var i=0; i<fielditems.length; i++) {
var itemSetValues = fielditems[i];
for (var j=0; j<itemSetValues.length; j++) {
var itemvalue = itemSetValues[j]; // notice the case
for (var k=0; k<itemvalue.length; k++) {
alert(itemvalue[k]);
}
}
}

for..in is for objects ({}), not for arrays ([]).
You need to use a standard for loop.
for(var i = 0, iLen = fielditems.length; i < iLen; i++){
var iItem = fielditems[i];
for(var j = 0, jLen = iItem.length; j < jLen; j++){
var jItem = iItem[j];
alert(jItem[0]); // you can also add another loop here, if this will have more elements
}
}
NOTE:
for(var i = 0, iLen = fielditems.length; i < iLen; i++)
is better than:
for(var i = 0; i < fielditems.length; i++)
because fielditems.length isn't requested each loop, just once at the start.