Develop Reference

How do I filter the data sent by firestore

How do I filter the data in collection in Firestore
If the first letter is "+" then I want to get filtered in Income section if the first letter is "-" then I want to get filtered in Expenditure Section
I tried this, but not working:
const getUsers = async()=>{
total_income_amount = await db.collection("users").get().then((querySnapshot) => {
const sum = querySnapshot.docs.filter((item) => item > 0).reduce((a, b) => a + b.data().amount, 0)
return sum
})
}
I am getting the output as 0
and I want the output with two decimal places
EDIT
Here's my code:
total_amount = db.collection("users").get().then((querySnapshot) => {
var total_sum = 0;
var income_sum = 0;
var exp_sum = 0;
querySnapshot.docs.forEach(doc => {
const amount = doc.data().amount;
amount >= 0.0? income_sum += amount : exp_sum -= amount;
total_sum += amount;
});
return {total: total_sum, income: income_sum, expense: exp_sum }
}).finally(result => console.log("Total: ", result));

You can loop through the list of values and append the values once rather than looping through it 5 times with a reduce & filter
total_amount = db.collection("users").get().then((querySnapshot) => {
var total_sum = 0;
var income_sum = 0;
var exp_sum = 0;
querySnapshot.docs.forEach(doc => {
const amount = doc.data().amount;
amount >= 0.0? income_sum += amount : exp_sum -= amount;
total_sum += amount;
});
return {total: total_sum, income: income_sum, expense: exp_sum }
})
.finally(result => console.log("TOTALS", result);
EDIT
It's not good to make major changes to your Question
but in general, you can truncate all number's to a decimal place using toFixed() on the final output
https://www.w3schools.com/jsref/jsref_tofixed.asp
UPDATE
Ensure your numbers are converted to real numbers from user inputs with Number(value) if the typeof returned is not a number, you can know if it is valid or not.
Once this has been done, ensure you return the correct calls as needed as scripts also only fire once.
when rendering values inside HTML, you want to use an embedded <span> tag with the appropriate id tag rather than editing it via javascript

Javascript | Floating point numbers + interval loop

I have a floating point number (for example): 0.004178174922295
How could I get the decremental function to make a calculations from this number to 0 in specific amount of time (for example 1 second)?
Thanks.
Expected values:
0.004178174922295
0.004178174922294
0.004178174922293
...
0

As raina77ow and others pointed out in the comments, operations with decimal numbers are problematic in JS, approximations are made and the results may be inexact.
A workaround would be turn the infinitesimals into big integral numbers, work with them and convert them back at the end.
Is this what you were looking for? Please let me know.
EDIT
You can ask for the countdown to be done in a certain amount of time, it does work with reasonable numbers, but in Javascript the minimum interval is of 10 milliseconds, you can't call intervals shorter than that. With the example number you gave, 0.004178174922295, it's like counting down from 4178174922295 to zero. That would requiere almost 1325 years in 10 millisecond intervals (if my math is correct, either way I expect you were going to pass a much shorter lapse).
function infinitesimalCountDown(num, seconds) {
// I create a coeficient to convert the decimal to an int
// Will be a big number starting with "1" and followed by a bunch of zeroes
let coefString = '1';
for(let i=0; i<num.toString().length-2; i++) {
coefString += '0';
}
const coef = Number(coefString);
// This has the digits from the original original but it's an int
let counter = Math.round(num*coef);
// Now I can just treat it as an int and convert it back for the output
const icdInterval = setInterval(() => {
counter--;
console.log(counter/coef);
if(counter <= 0) clearInterval(icdInterval);
}, Math.round(seconds*1000/counter));
}
console.log("It works with a short number");
infinitesimalCountDown(0.0041, 10);
setTimeout(() => {
console.log("It doesn't work with a long number");
infinitesimalCountDown(0.004178174922295, 3000);
}, 12 * 1000);
If you are fine with the steps being the necessary for Javascript to be able to process it, you can do the following:
function infinitesimalCountDown(num, seconds) {
let coefString = '1'
for(let i=0; i<num.toString().length-2; i++) {
coefString += '0'
}
const coef = Number(coefString)
let counter = Math.round(num*coef)
let steps = seconds * 1000 / counter
steps = steps < 100 ? 100 : steps
let step = 1
if(steps == 100) {
step = counter / ((seconds * 1000) / steps)
}
console.log(step)
const icdInterval = setInterval(() => {
counter -= step;
if(counter <= 0) {
counter = 0
clearInterval(icdInterval)
}
console.log(counter/coef)
}, steps)
}
infinitesimalCountDown(0.004178174922295, 5)

If you can represent the input number as number type (so not have many decimals), you can do this using normal number subtraction.
Here, the important thing is to get the unit to be subtracted. You can get the unit using Math.pow.
And from this floating point guide, it is needed to round the counted number and that can be done using toFixed function.
let input = 0.004178174922295;
const decimalCount = input.toString().length - 2;
const unit = Math.pow(10, -1 * decimalCount);
console.log(input);
const loopInterval = setInterval(() => {
input = Number((input - unit).toFixed(decimalCount));
console.log(input);
if (input == 0) {
clearInterval(loopInterval);
}
}, 1000);
And if the input number has many decimals so it is received as string type (not able to present using number type), it is needed to do the subtraction using string as follows.
const input = '0.0041781749222934534534534535';
const inputArr = input.split('.');
const intNum = inputArr[0]; // Present integer
let decimals = inputArr[1]; // Present decimals after '.'
const unit = 1;
function replaceAt(str, index, replace) {
return str.substring(0, index) + replace + str.substring(index + 1);
}
console.log(input);
const loopInterval = setInterval(() => {
let index = decimals.length - 1;
while (parseInt(decimals[index]) < unit) {
decimals = replaceAt(decimals, index --, '9');
}
decimals = replaceAt(decimals, index, `${parseInt(decimals[index]) - unit}`);
console.log(`${intNum}.${decimals}`);
}, 1000);

Javascript adding multiple arrays in a loop

I am trying to add multiple arrays in javascript.
Here are my arrays I have made, and are working.
function getAmountSpent(){
var amountSpent = ((Math.random() * 500) + 1);
return amountSpent.toFixed(2)
}
function getGift(){
var gift = ((Math.random()* 50) + 1);
return gift.toFixed(2)
}
var names = ["Jeremy","Arun","Alisa","Rohan","Dana"];
var spent = [];
for (let i = 0; i < 5; i++) {
spent.push(getAmountSpent());
}
var gifts = [];
for (let i = 0; i<5; i++) {
gifts.push(getGift());
}
What I need help with is adding these arrays in a new function. I have began writing the code, and I am not sure what is wrong.
var totals =[];
for (let i=0; i<5; i++) {
totals.push(getSumTotals())
}
function getSumTotals(a){
totals= spent+(spent * gifts);
return totals.toFixed(2)
}
From what you can see, I am trying to add up the totals much like this:
totals[0] = spent[0] + (spent[0] * gifts[0]);
totals[1] = spent[1] + (spent[1] * gifts[1]);
totals[2] = spent[2] + (spent[2] * gifts[2]);
totals[3] = spent[3] + (spent[3] * gifts[3]);
totals[4] = spent[4] + (spent[4] * gifts[4]);
if it helps, the professor added guided instructions for function getSumTotals(a) stating:
This function will return the sum of the elements in array a.
You will be passing the array that holds your totals to
the parameter a. Be sure to treat the values in a as numbers.
I am not sure if this helps but here is the output to my document.
Current Total should equal (spent) + (spent * gifts). For instance, for Jeremy in this example, current total should equal:
$36.55 + ($36.55*0.0626) = $38.83. Since there are many variables involved, I am not 100% sure what I should write for function getSumTotals(a)
The parameter "a" is a placeholder because I am not sure how many parameter values I need, and the proper format I need to use.

As for the code...
You're both
not passing an index to getSumTotals
not using this parameter within getSumTotals to access your spent and gifts arrays
var totals =[];
for (let i=0; i<5; i++) {
totals.push(getSumTotals(i)) // you were missing i
}
function getSumTotals(idx) { // I took liberties to rename this
totals = spent[idx] + (spent[idx] * gifts[idx]);
return totals.toFixed(2);
}
Now for the Math...
All that said, this math of spent[i] + spent[i] * gifts[i] doesn't make much sense either. Was this specified in the problem?

you may use like this
defined gifts
gifts=[45,43,32];
defined spends
spends=[43,32,21];
this is the getSumTotal funtion
getSumTotal=(x)=>(x.a+x.b)
this is where added
totals=gifts.map((d1,i)=>{
return fu({a:gifts[i],b:spends[i]})
})

I understand this is your assignment, however - if the idea is to both generate arrays, and then add them together, it is a redundant step. Just use the name array to iterate once and do all your calculations within that single loop.
Here, I had some fun and took some liberties, but hopefully you see why multiple arrays are redundant.
function getSumTotals() {
const getAmountSpent = () => Math.random() * 500 + 1;
const getGift = () => Math.random() * 50 + 1;
const names = ["Jeremy", "Arun", "Alisa", "Rohan", "Dana"];
let totals = []
names.forEach((name, i) => {
let spent = getAmountSpent()
let gifts = getGift()
let $$$ = (spent + spent * gifts).toFixed(2);
totals[i] = $$$
console.log(`${name} cost me $${$$$}${'!'.repeat(($$$/1000) | 1)}`)
});
return totals;
}
getSumTotals()

Note, that toString returns a type of "String", but not "Number".
When you try to sum a number with string, you get a concatenated string "1" + 2 = "12"
To turn a string into Number, you must use a Number("str") function, or just a bunary + before the string:
console.log( "1" + 2 );
console.log( Number("1") + 2 );
console.log( +"1" + 2 );
Also, you use the same loop 3 times, but can use just one loop instead, and call all functions inside the one loop. And use your array.length instead of fixed number 5:
let names = ["Jeremy", "Arun", "Alisa", "Rohan", "Dana"];
let spent = [];
let gifts = [];
let totals = [];
for (let i = 0; i < names.length; i++) {
spent.push( getAmountSpent() );
gifts.push( getGift() );
totals.push( getSumTotals(i) );
}
console.log( totals );
function getAmountSpent() {
return rand(1, 500, 2);
}
function getGift() {
return rand(1, 50, 2);
}
function getSumTotals(i) {
return +( spent[i] * ( 1 + gifts[i] ) ).toFixed(2);
}
function rand(from, to, fixed = 0){
return +(Math.random()*( to - from ) + from).toFixed(fixed);
}
P.s. Math.random() returns a number between 0 (included) and 1 (not included). If you need a random number between (example) 20 and 100, Math.random()*(100-20) will give a number between 0 and 80. After adding +20 to the result, you get a number from 20 to 100. That's what does this formula Math.random()*( to - from ) + from
P.P.s. Another way, to get the same thing:
var names = ["Jeremy", "Arun", "Alisa", "Rohan", "Dana"].reduce( (prev, elem) => {
let spent = rand(1, 500, 2);
let gift = rand(1, 50, 2);
prev[elem] = new UserData( spent, gift );
return prev;
}, {});
console.log( "Jeremy spent: " + names.Jeremy.spent );
console.log( names );
function rand(from, to, fixed = 0){
return +(Math.random()*( to - from ) + from).toFixed(fixed);
}
function UserData(spent, gift){
this.spent = spent;
this.gift = gift;
this.total = +(spent * ( 1 + gift )).toFixed(2);
}
/* Google → Array reduce, Constructor functions */

function getAmountSpent(){
let amountSpent = ((Math.random() * 500) + 1);
return Number(amountSpent.toFixed(2))
}
function getGift(){
let gift = ((Math.random()* 50) + 1);
return Number(gift.toFixed(2))
}
let names = ["Jeremy","Arun","Alisa","Rohan","Dana"];
let spent = [];
let gifts = [];
let totals =[];
for (let i = 0; i < names.length; i++) {
spent.push(getAmountSpent());
gifts.push(getGift());
totals[i] = (spent[i]+(spent[i] * gifts[i])).toFixed(2);
totals[i] = parseFloat(totals[i])
}
Hi there
I don't think you need a function to add the totals. you just need to loop through and assign totals[i] to spent[i] + (spent[i] * gifts[i]).
then you can use the parseFloat and toFixed function to change the string to a number. remember toFixed() function turns numbers to string. so you need to use the parseFloat to change it to number again as shown in the code above. or you can come up with an easy way of changing it to number. I hope this helps!

Can't figure out parseInt, even after research in JS and JQ [closed]

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Closed 8 years ago.
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I have an object with a property containing a large string. This property has a value with random numbers generated earlier in the script in the format x , x , x , x ... (isn't and can't be an array because of other needs for the variable within the program) and so on. I am trying to get the sum of these numbers and my first thought was to use parseInt() to do this by splitting them all up then adding them together, but when I do this it only returns the first number. Is this what I should do but I'm just doing it wrong? Or is there another function that would make this easier?
The program is a blackjack game I'm making to see how well i understand everything I am learning.
Here is the function i am trying to make to see if the user busts when taking a hit (not much so far because i can't figure out the parseInt thing)
'
function checkBust() {
var total = parseInt(user.hand, 10);
}
'
the user object
'
var user = {
hand: dealUser()
};
'
and the functions to set the object property
function randomCard() {
// random number between 0 and 10
var j = Math.random() * 10;
// round that number into a var called card
var card = Math.round(j);
// if card is 0, assign a J Q or K by making a random number again
if (card === 0) {
//another random number
var k = Math.random() * 10;
// checks random number and assign J Q or K
if (k <= 4) {
card = 'J';
} else if (k <= 7) {
card = 'Q';
}
else {
card = 'K';
}
}
// value of the function is a single card
return card;
}
function dealUser() {
// empty array to store cards
var x = [];
// var to start for loop
var i = 0;
// start for loop
for (i; i < 2; i++) {
// add a random card to the i^th index of x
x[i] = randomCard();
}
// value for function is array of two cards x[0] , x[1]
var cards = x[0] + " , " + x[1];
return cards;
}

parseInt will stop parsing when it reaches a non numeric character.
parseInt('1234,5678', 10); // => 1234
// since a comma (,) is not a numeric character, everything after is ignored.
You have to split the string into an array of strings using the comma as the delimiter:
'1234,5678'.split(','); // => ['1234', '5678'];
Then parse each element of the array to convert them to numbers and then you can sum them.
Here's how I'd do it:
var nums = "1,2,3,4,5";
var sum = nums.split(',').reduce(function(memo, num) {
return memo + parseInt(num, 10);
}, 0);
console.log(sum); // => 15
That should work. See jsbin example.
Note the split parameter needs to match the delimiters you use in your string. for this example ',' is appropriate. For your example you might need /\s*,\s*/.
Unrelated
Since you provided an example of code I can see that you're spending a lot of effort attempting to duck punch and transform the values to the types you need instead of exposing the types in an object. Might I suggest:
function Stack(cards) {
this.cards = cards || [];
}
Stack.prototype.toString = function() {
return this.cards.join(' , ');
};
Stack.prototype.sum = function() {
return this.cards.reduce(function(memo, card) {
return memo + parseInt(card, 10);
}, 0);
};
function randomCard() {
return Math.floor(Math.random() * 13) + 1;
}
Stack.dealHand = function() {
var card1 = randomCard(), card2;
do { card2 = randomCard(); } while (card1 === card2);
return new Stack([card1, card2]);
};
// Example
var hand = Stack.dealHand();
console.log(hand + ' = ' + hand.sum()); // => '3 , 11 = 14'

Random Number with javascript or jquery

I am trying to make a script to pick random number between two numbers . but it picks same number sometimes. i donot want to repeat same number until array is finished .
Here is my code
$(document).ready(function () {
abc();
test = array();
function abc() {
res = randomXToY(1, 10, 0);
$('#img' + res).fadeTo(1200, 1);
//$(this).addClass('activeImg');
//});
setTimeout(function () {
removeClassImg(res)
}, 3000);
}
function removeClassImg(res) {
$('#img' + res).fadeTo(1200, 0.1);
//$('#img' + res).removeClass('activeImg');
abc();
}
function randomXToY(minVal, maxVal, floatVal) {
var randVal = minVal + (Math.random() * (maxVal - minVal));
return typeof floatVal == 'undefined' ? Math.round(randVal) : randVal.toFixed(floatVal);
}
});
Does Anybody have idea about this ...

You'll have to maintain a list of numbers that have already been generated, and check against this list. Re-generate a new number if you find a dupe.

If you do not want the random numbers repeating themselves you have to keep track of the some way.
If you have the range you are dealing with is relatively small, you can create an array with all possible results and simply randomly pick out of it.
function Randomizer(minVal, maxVal, floatVal){
var possible_results = []; // for larger arrays you can build this using a loop of course
var randomization_array = [];
var count = minVal;
var incrementor = floatVal || 1; // set the distance between possible values (if floatVal equals 0 we round to 1)
while (count <= maxVal) {
possible_results.push(count);
count += incrementor;
}
this.run = function(){
// if randomization_array is empty set posssible results into it
randomization_array = randomization_array.length ? randomization_array : $.merge(randomization_array, possible_results);
// pick a random element within the array
var rand = Math.floor(Math.random()*randomization_array.length);
// return the relevant element
return randomization_array.splice(rand,1)[0];
}
}
and in order to use it (it creates a specialized object for each possible range):
rand = new Randomizer(1,10,0);
rand.run();
note that this approach does not work well for very large ranges