"name": [
{
"name": "test1"
},
{
"name": "test2"
},
{
"name": "test3"
},
{
"name": "test1"
},
]
I have the above created by nodejs. During array push, I would like to remove duplicated arrays from the list or only push the name array if the individual array does not exist.
I have tried below codes but it changes the array.
var new = [];
for (var i =0;i<name.length;i++){
new['name'] = name[i].name;
}
The easiest way is probably with Array.prototype.reduce. Something along these lines, given your data structure:
obj.name = Object.values(obj.name.reduce((accumulator, current) => {
if (!accumulator[current.name]) {
accumulator[current.name] = current
}
return accumulator
}, {}));
The reduce creates an object that has keys off the item name, which makes sure that you only have unique names. Then I use Object.values() to turn it back into a regular array of objects like in your data sample.
the solution can be using temp Set;
const tmpSet = new Set();
someObj.name.filter((o)=>{
const has = tmpSet.has(o.name);
tmp.add(o.name);
return has;
});
the filter function iterating over someObj.name field and filter it in place if you return "true". So you check if it exists in a tmp Set & add current value to Set to keep track of duplicates.
PS: new is a reserved word in js;
This should do it
const names = ['John', 'Paul', 'George', 'Ringo', 'John'];
let unique = [...new Set(names)];
console.log(unique); // 'John', 'Paul', 'George', 'Ringo'
https://wsvincent.com/javascript-remove-duplicates-array/
Related
I have an State varaible with array of objects like this.
type State = {
Dp: ArrayDataProvider<string, Message>;
};
Inside Dp i will have data which will hold the data in the form of array like this.
[{
"id": 1,
"name": "January",
"abc": abc,
"xyz": xyz
}, {
"id": 2,
"name": "February",
"abc": abc,
"xyz": xyz
}]
I want to replace the object which is having id 2 with the different object and i want to have my object like this .
[{
"id": 1,
"name": "January",
"abc": abc,
"xyz": xyz
}, {
"id": 2,
"name": "New month",
"abc": 1234abc,
"xyz": someVlaue
}]
how to do it in efficient way with typescript in react.
I have done something like this but not working
const data = this.state.Dp?.data.slice();
const index = data.findIndex(currentItem => {
return currentItem.id === updateData[0].id;
});
data[index] = updateData;
this.state.Dp.data = data;
this.setState({ Dp: this.state.Dp });
I use map to do this:
const data = this.state.Dp?.data.map(currentItem => {
return currentItem.id === updatedItem.id ? updatedItem : currentItem;
})
map creates a new array with the items from the previous array, but it gives you an opportunity to make adjustments to the items in the new array as it iterates through them. In my example, I'm checking the id of the item to see if it's the one you want to update, and swapping in your updatedItem if the ids match.
I'm not sure about the TypeScript part, to be honest. I haven't worked with it yet.
Note - I'm not sure what form your updateData is in, so you might have to adjust that. It seems like you want it to be an object, but in one of your lines you're treating it like an array.
Use findIndex to find index of the object where id is equal 2, then replace new object to that place.
let tempArray = [...array];
const index = tempArray.findIndex((element) => element.id === 2);
tempArray[index] = {
id: 2,
name: "New month",
abc: "1234abc",
xyz: "someVlaue"
};
setArray(tempArray);
In my state I have an object called foodLog which holds all entries a user enters with one of the keys being foodSelectedKey and I'm trying to return all entries that have a matching value from that key with a different array called foodFilter.
However, this doesn't work and errors out saying foodLog.filter() isn't a function - I've looked this up and it's because it's an Object (I think). Any help would be greatly appreciated!
state = {
// log food is for the logged entries
foodLog: {},
// used for when filtering food entries
foodFilter: [],
};
findMatches = () => {
let foodLog = this.state.foodLog;
let foodFilter = this.state.foodFilter;
let matched = foodLog.filter((item) => {
return foodLog.foodsSelectedKey.map((food) => {
return foodFilter.includes(food);
});
});
};
I guess the reason behind the error Is not a function is that the object can not be looped. By that it means you can not iterate an object with differend variables inside, if it has no index to be iterated like an array. The same goes for map(), find() and similar functions which MUST be run with arrays - not objects.
As far as I understand you have an object named foodLog which has an array named foodsSelectedKey. We need to find intersected elements out of foodFilter with the array. This is what I came up with:
state = {
// log food is for the logged entries
foodLog: {
foodsSelectedKey: [
{ id: 1, name: "chicken" },
{ id: 2, name: "mashroom" }
]
},
// used for when filtering food entries
foodFilter: [
{ id: 1, name: "chicken" },
{ id: 2, name: "orange" }
]
};
findMatches = () => {
let foodLog = this.state.foodLog;
let foodFilter = this.state.foodFilter;
let matched = foodLog.foodsSelectedKey.filter((key) =>
{
for (let i=0; i<foodFilter.length;i++){
if(foodFilter[i].name===key.name)
return true
}
return false;
}
);
return matched;
};
The Output is filtered array, in this case, of one element only:
[{
id: 1
name: "chicken"
}]
In order to check the output - run console.log(findMatches()). Here is the CodeSandbox of the solution. (check console at right bottom)
Newbie here and this is a project I'm building to learn. I'm going around in circles so forgive my ignorance please. I'm now not even sure that what I want to do is possible. I also understand that there are probably better ways to achieve my ultimate goal but this is what I have.
I have an array that includes some user input.
"participants": [ {
"name": "Cristina",
"email": "cristina#gmail",
"yourPerson": "Richard",
"spouseEmail": "Richard#gmail" } ] }
I want to pull the "name" and "youPerson" values and use them as a key:value pair. So name would be the key and yourPerson would be the value.
I thought I could use a forEach but no matter what I do I either get an undefined array or I copy the entire array, not just those two fields.
here is my code at the moment:
participantArray = [];
namePlusSpouseArray = [];
submitParticipant() {
this.participantArray.push(this.participantForm.value);
console.log(this.participantArray)
this.createNamePlusSpouseArray();
}
createNamePlusSpouseArray() {
this.participantArray.forEach(name => {
this.namePlusSpouseArray.push(this.participantArray[name]);
console.log(this.namePlusSpouseArray)
});
}
Not sure if you want a result array of key value pairs, or you want 1 object/map/dictionary/lookup of name -> youPerson
Assuming you want an array containing key value pairs, you can use map
this.namePlusSpouseArray = this.participantArray.map(participant => ({
[participant.name]: participant.youPerson
});
If you want a lookup of name -> youPerson, the "namePlusSpouseArray" shouldn´t be an array but instead just an object
namePlusSpouseLookup = {};
this.participantArray.forEach(participant => {
this.namePlusSpouseLookup[participant.name] = participant.youPerson;
});
The simplest solution is:
const participantArray = {
"participants": [ { "name": "Cristina", "email": "cristina#gmail", "yourPerson": "Richard", "spouseEmail": "Richard#gmail" } ] };
const createPair = participants => {
return participants.map(participant =>
({ [participant.name]: participant.yourPerson}))
}
console.log(createPair(participantArray.participants));
Given a list:
let names = [{name: "bobby"}, {name: "sydney"}, {name: "Paul"}, {name: "Grace"}
I want the output to be ["bobby", "sydney", "Paul", "Grace"]
Here is what I have tried:
var items = Object.keys(names).map(function(i) {
return names[i];
})
const items = Object.keys(names).map((key)=>names[key]);
this.setState({items});
console.log(this.state.items);
names.map(({ name }) => name)
const names = [{
name: "bobby"
}, {
name: "sydney"
}, {
name: "Paul"
}, {
name: "Grace"
}];
const keys = names.map(({
name
}) => name);
console.log(keys);
A note about react keys, they should be unique within the rendered siblings, i.e. they should be unique within the dataset. Names alone may not provide sufficient uniqueness.
A second note, you might not want to generate your react keys separately from where you need them, i.e. generally they are created when you are mapping JSX.
This is not really related to React. You can do that with JavaScript, for instance using API like map().
Here is an example:
let arr = names.map(obj => obj.name);
Let's say I have this Json ..
{
"name": "Mark",
"gender": "male",
"account1": {
"accountNo": 1201,
"balance": 300
},
"account2": {
"accountNo": 1354,
"balance": 5000
}
}
What I expect is like ..
$scope.myArray = [
{
"accountNo": 1201,
"balance": 300
},
{
"accountNo": 1354,
"balance": 5000
}
];
In AngularJS, how can I pick some part of Json data and push it into an array iteratively( I mean, when I have account1, account2 account3 or more, it can still add them into the array).
You could normally just assign the array over, but in this scenario that is not an option because your array is psuedo.
Ideally you would like to be able to do what this answer (related question) does: How to return and array inside a JSON object in Angular.js which is simply
$scope.myArray = json.accounts;
However, as noted, you do not have an accounts array so you need to make one.
var accounts = [];
for(var key in json){
if( !json.hasOwnProperty(key) // skip prototype extensions
|| !json[key].hasOwnProperty("accountNo") //skip non account objects
) continue;
accounts.push(json[key]);
}
And now you may use this array
$scope.myArray = accounts;
You can access Json data like an array. Like var foo = { ... , 'bar' = 'value', ... } you could get foo value by doing this for['bar']. So, by knowing this, you simply do something like
var arr = [];
for (var i = 0; i < 10; i++) {
arr.push(foo['account'+i]);
}
Although, this has nothing to do with angularjs.