I'm working with two different lists(arrays) which, in theory, are supposed to store different kind of information. Down below are the two arrays.
let items = ["Buy Food", "Cook Food", "Eat Food"];
let workItems = [];
The code below is responsible for assigning values to each array, based on the value(name of the list to which the item belongs) passed to the function .
app.post("/", function(req, res){
let item = req.body.newItem;
var a = req.body.list;//this variable stores the list name
var b = "Work";
console.log(a, b);// When 'a' is "Work", this prints: "Work" "Work"
//My problem starts here
//When the value stored in 'a' is "Work", the comparison below never returns true, even though they're >//the same thing.
if ( a === b){
//never got here!
workItems.push(item);
console.log(workItems);//At this stage it shouldn't be an ampty array
res.redirect ("/work");
} else{
items.push(item);
res.redirect ("/");
console.log(workItems)
}
});
Terminal: terminal
complete code link https://controlc.com/8931bb24
On your screenshot, it looks like there are two spaces between the Work Work console output. One possible reason is that you actually get Work as variable a. If you want to ignore this you can use trim():
if (a.trim() === b)
Moreover, if you are interested only in semantic meaning and not the case to can compare to a lower-cased string:
if (a.trim().toLowerCase() === 'work')
If that is not working for you, you should check more thoroughly what is the value of a, most probably, it's not 'Work' exactly.
Related
From my database I have set one person to be "banned" but instead of printing the value "1" it leaves it empty and even when the value is 0 it still leaves it empty.
for (const dataItem of res.data.data) {
var IsBanned = 0 ;
if(dataItem.banned === true){
this.setState({IsBanned: this.state.count +1})
console.log("Local", IsBanned);
}
}
console.log
any advice is appreciated
this.setState() is async function so it does take some time to update value in state.
You can utilise 2nd argument of setState which is callback
this.setState({IsBanned: this.state.count +1},()=>console.log("Local", this.state.IsBanned);)
Here you have taken isBanned as local variable, but trying to update it as state variable. So you first need to decide whether to keep it in state or in local.
1.This code may fail to update the counter:
this.setState({IsBanned: this.state.count +1})
console.log("Local", IsBanned);
2.You have to use this because setState() that accepts a function rather than an object.
this.setState((state) => ({IsBanned: state.counter + 1}));
I'm trying to select certain keys from an JSON array, and filter the rest.
var json = JSON.stringify(body);
which is:
{
"FirstName":"foo",
"typeform_form_submits":{
"foo":true,
"bar":true,
"baz":true
},
"more keys": "foo",
"unwanted key": "foo"
}
Want I want:
{
"FirstName":"foo",
"typeform_form_submits":{
"foo":true,
"bar":true,
"baz":true
}
}
I've checked out How to filter JSON data in node.js?, but I'm looking to do this without any packages.
Now you can use Object.fromEntries like so:
Object.fromEntries(Object.entries(raw).filter(([key]) => wantedKeys.includes(key)))
You need to filter your obj before passing it to json stringify:
const rawJson = {
"FirstName":"foo",
"typeform_form_submits":{
"foo":true,
"bar":true,
"baz":true
},
"more keys": "foo",
"unwanted key": "foo"
};
// This array will serve as a whitelist to select keys you want to keep in rawJson
const filterArray = [
"FirstName",
"typeform_form_submits",
];
// this function filters source keys (one level deep) according to whitelist
function filterObj(source, whiteList) {
const res = {};
// iterate over each keys of source
Object.keys(source).forEach((key) => {
// if whiteList contains the current key, add this key to res
if (whiteList.indexOf(key) !== -1) {
res[key] = source[key];
}
});
return res;
}
// outputs the desired result
console.log(JSON.stringify(filterObj(rawJson, filterArray)));
var raw = {
"FirstName":"foo",
"typeform_form_submits":{
"foo":true,
"bar":true,
"baz":true
},
"more keys": "foo",
"unwanted key": "foo"
}
var wantedKeys =["FirstName","typeform_form_submits" ]
var opObj = {}
Object.keys(raw).forEach( key => {
if(wantedKeys.includes(key)){
opObj[key] = raw[key]
}
})
console.log(JSON.stringify(opObj))
I know this question was asked aways back, but I wanted to just toss out there, since nobody else did:
If you're bound and determined to do this with stringify, one of its less-well-known capabilities involves replacer, it's second parameter. For example:
// Creating a demo data set
let dataToReduce = {a:1, b:2, c:3, d:4, e:5};
console.log('Demo data:', dataToReduce);
// Providing an array to reduce the results down to only those specified.
let reducedData = JSON.stringify(dataToReduce, ['a','c','e']);
console.log('Using [reducer] as an array of IDs:', reducedData);
// Running a function against the key/value pairs to reduce the results down to those desired.
let processedData = JSON.stringify(dataToReduce, (key, value) => (value%2 === 0) ? undefined: value);
console.log('Using [reducer] as an operation on the values:', processedData);
// And, of course, restoring them back to their original object format:
console.log('Restoration of the results:', '\nreducedData:', JSON.parse(reducedData), '\nprocessedData:', JSON.parse(processedData));
In the above code snippet, the key value pairs are filtered using stringify exclusively:
In the first case, by providing an array of strings, representing the keys you wish to preserve (as you were requesting)
In the second, by running a function against the values, and dynamically determining those to keep (which you didn't request, but is part of the same property, and may help someone else)
In the third, their respective conversions back to JSON (using .parse()).
Now, I want to stress that I'm not advocating this as the appropriate method to reduce an object (though it will make a clean SHALLOW copy of said object, and is actually surprisingly performant), if only from an obscurity/readability standpoint, but it IS a totally-effective (and mainstream; that is: it's built into the language, not a hack) option/tool to add to the arsenal.
I have a JSON file of 2 discord client IDs `{
{
"premium": [
"a random string of numbers that is a client id",
"a random string of numbers that is a client id"
]
}
I have tried to access these client IDs to do things in the program using a for loop + if statement:
for(i in premium.premium){
if(premium.premium[i] === msg.author.id){
//do some stuff
}else{
//do some stuff
When the program is ran, it runs the for loop and goes to the else first and runs the code in there (not supposed to happen), then runs the code in the if twice. But there are only 2 client IDs and the for loop has ran 3 times, and the first time it runs it goes instantly to the else even though the person who sent the message has their client ID in the JSON file.
How can I fix this? Any help is greatly appreciated.
You may want to add a return statement within your for loop. Otherwise, the loop will continue running until a condition has been met, or it has nothing else to loop over. See the documentation on for loops here.
For example, here it is without return statements:
const json = {
"premium": [
"aaa-1",
"bbb-1"
]
}
for (i in json.premium) {
if (json.premium[i] === "aaa-1") {
console.log("this is aaa-1!!!!")
} else {
console.log("this is not what you're looking for-1...")
}
}
And here it is with return statements:
const json = {
"premium": [
"aaa-2",
"bbb-2"
]
}
function loopOverJson() {
for (i in json.premium) {
if (json.premium[i] === "aaa-2") {
console.log("this is aaa-2!!!!")
return
} else {
console.log("this is not what you're looking for-2...")
return
}
}
}
loopOverJson()
Note: without wrapping the above in a function, the console will show: "Syntax Error: Illegal return statement."
for(i in premium.premium){
if(premium.premium[i] === msg.author.id){
//do some stuff
} else{
//do some stuff
}
}
1) It will loop through all your premium.premium entries. If there are 3 entries it will execute three times. You could use a break statement if you want to exit the loop once a match is found.
2) You should check the type of your msg.author.id. Since you are using the strict comparison operator === it will evaluate to false if your msg.author.id is an integer since you are comparing to a string (based on your provided json).
Use implicit casting: if (premium.premium[i] == msg.author.id)
Use explicit casting: if (premium.premium[i] === String(msg.author.id))
The really fun and easy way to solve problems like this is to use the built-in Array methods like map, reduce or filter. Then you don't have to worry about your iterator values.
eg.
const doSomethingAuthorRelated = (el) => console.log(el, 'whoohoo!');
const authors = premiums
.filter((el) => el === msg.author.id)
.map(doSomethingAuthorRelated);
As John Lonowski points out in the comment link, using for ... in for JavaScript arrays is not reliable, because its designed to iterate over Object properties, so you can't be really sure what its iterating on, unless you've clearly defined the data and are working in an environment where you know no other library has mucked with the Array object.
i am trying to accept array parameters from the frontend through swagger and do some function over as shown where i have sent a value in ingredient and no value in applicant
let applicant = req.swagger.params.applicant.value;
console.log(applicant);
console.log(typeof applicant);
let ingredient = req.swagger.params.ingredient.value;
console.log(ingredient);
console.log(typeof ingredient);
the following gets logged
[ '' ]
object
['somevalue']
object
i want to create a function such that
if (applicant && applicant !== ['']){
//do something
}
if (ingredient && ingredient !== ['']){
// do something
}
but this doesn't seem to work. is there any other way to go around this
The basic problem with your approach is that is doesnt consider for the array to have an empty string. when you check with if(applicant){//do something} you do not consider that the array might have an empty string but string nonetheless.
this is why you actually need to check for the array length to determine if it is empty or not and then check for the first element is an empty string or not.
so ur code would look something like:
if (applicant && applicant.length && applicant[0]!== ''){
//do something
}
There are two collections products and stock in my database.Each product have multipple stock with different supplier and attributes of products.
I have selected the products from products collection and run a loop for each product. I need to append price and offer price from the stock collection to products i have selected already.
I think the for loop compleated its execution before executiong the find method on stock collection.I need to execute everything in the loop in serial manner(not asynchronous). Please check the code below and help me to solve this. I'm new in node.js and mongodb
collection = db.collection('products');
collection.find().toArray(function(err, abc) {
var finalout = [];
for( var listProducts in abc){
var subfinal = {
'_id' :abc[listProducts]['_id'],
'min_price' :abc[listProducts]['value']['price'],
'stock' :abc[listProducts]['value']['stock'],
'name' :abc[listProducts]['value']['name'],
'price' :'',
'offer_price' :'',
};
collection = db.collection('stock');
collection.find({"product":abc[listProducts]['_id'] ,"supplier":abc[listProducts]['value']['def_supplier']}).toArray(function(err, newprod) {
for( var row in newprod){
subfinal['price'] = newprod[row]['price'];
subfinal.offer_price = newprod[row]['offer_price'];
}
finalout.push(subfinal);
});
}
console.log(finalout);
});
Yes, the loop is running and starting the get requests on the database all at the same time. It is possible, like you said, to run them all sequentially, however it's probably not what you're looking for. Doing it this way will take more time, since each request to Mongo would need to wait for the previous one to finish.
Considering that each iteration of the loop doesn't depend on the previous ones, all you're really looking for is a way to know once ALL of the operations are finished. Keep in mind that these can end in any order, not necessarily the order in which they were initiated in the loop.
There's was also an issue in the creation of the subfinal variable. Since the same variable name is being used for all iterations, when they all come back they'll be using the final assignment of the variable (all results will be written on the same subfinal, which will have been pushed multiple times into the result). To fix that, I've wrapped the entire item processing iteration into another function to give each subfinal variable it's own scope.
There are plenty of modules to ease this kind of management, however here is one way to run some code only after all the Mongo calls are finished using a counter and callback that doesn't require any additional installs:
var finished = 0; // incremented every time an iteration is done
var total = Object.keys(abc).length; // number of keys in the hash table
collection = db.collection('products');
collection.find().toArray(function(err, abc) {
var finalout = [];
for( var listProducts in abc){
processItem(listProducts);
}
});
function processItem(listProducts) {
var subfinal = {
'_id' :abc[listProducts]['_id'],
'min_price' :abc[listProducts]['value']['price'],
'stock' :abc[listProducts]['value']['stock'],
'name' :abc[listProducts]['value']['name'],
'price' :'',
'offer_price' :'',
};
collection = db.collection('stock');
collection.find({"product":abc[listProducts]['_id'] ,"supplier":abc[listProducts]['value']['def_supplier']}).toArray(function(err, newprod) {
for( var row in newprod){
subfinal['price'] = newprod[row]['price'];
subfinal.offer_price = newprod[row]['offer_price'];
}
finalout.push(subfinal);
finished++;
if (finished === total) { // if this is the last one to finish.
allFinished(finalout);
}
});
}
function allFinished(finalout) {
console.log(finalout);
}
It could be written more concisely with less variables, but it should be easier to understand this way.