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How to display only the text in datalist and not the value?

Let suppose that we have the following datalist, and a js variable var carID = '':
<input list="options" #change='${carID = e.target.value}'>
<datalist id="options">
<option value="ID_1">Ferrari</option>
<option value="ID_2">Lamborghini</option>
<option value="ID_3">Jeep</option>
</datalist>
I'd like to show ONLY the car names in my options, and NOT the option values (that are the IDs of the cars), and have the ID of the selected car (the value of the selected option) stored in the variable, not the car name.
I tried different solutions, I post 2 of them (one totally wrong and one right but not complete, I 've found this one in other stack overflow questions):
wrong: it simply doesn't work, e.target.carID is ''.
<input list="options" #change="${carID = e.target.carID}">
<datalist id="options">
<option carID="ID_1" value="Ferrari"></option>
<option carID="ID_2" value="Lamborghini"></option>
<option carID="ID_3" value="Jeep"></option>
</datalist>
Ok it's working, but what if I have 2 cars with the same name and different id? Yes, the second car is ignored and if I select the 2nd car I store the 1st car's ID.
<input id='inputID' list="options" #change='${this.getValue}'>
<datalist id="options">
<option data-value="ID_1" value="Ferrari"></option>
<option data-value="ID_2" value="Lamborghini"></option>
<option data-value="ID_3" value="Jeep"></option>
<option data-value="ID_4" value="Jeep"></option>
</datalist>
js:
getValue(){
let shownValue = this.shadowRoot.getElementById('inputID').value;
let rightValue =
this.shadowRoot.querySelector("#options[value='"+shownValue+"']").dataset.value;
carID = rightValue;
}
I cannot use JQuery. Do you have any solutions? Thanks!

Your code #change='${carID = e.target.carID}' cannot work, as the right hand side of the event handler binding is not callable. You need to wrap it inside an anonymous function, e.g. like so: #change=${(e) => { this.carID = e.target.value }}
That being said, this is what I understood you want to do:
Have a list, where the user can choose from.
In the list, only display the name of the car, not the ID.
Store the selected car's ID in carID, not the name.
I see two ways to do that.
Option 1: Use <select>
If the list of cars is fixed, I think you will be best served using a <select height="1"> element, resulting in a drop down box. Including the little event handler, it looks something like this:
<select #change=${(e) => { this.carID = e.target.value }}>
<option value="ID_1">Ferrari</option>
<option value="ID_2">Lamborghini</option>
<option value="ID_3">Jeep</option>
<option value="ID_4">Jeep</option>
</select>
This will display the text from the text content of the <option> elements, but set the value of the <select> from the <option>'s value attribute, and by the virtue of the onchange event handler will set the carID field on the element.
You can even have two cars with different IDs, but the same name. Note however, that your users would not know, if the display text is the same, which of the two "Jeep" entries to choose. So that might not be a good idea (but I don't know your full use case).
Option 2: Use <input> with <datalist>
Now, if the list of cars is not fixed, i.e. the users are allowed to enter arbitrary data and the selection list is not for limiting their choices, but to help them (prevent typos, speed-up entry) you can use an <input> with an associated <datalist>. But the popup will display both, the <option>'s value and text content (if they are both defined and different). If you insist on only showing the name of the car, not the ID, then the name has to go in the value attribute of the <option> (or the text content). While you could put the ID in the dataset, you really don't need to.
In any case you'll need to map the value string back to the ID through your own code. This will only work if "cars and names" is a one-to-one (aka bijective) mapping, so no two cars with the exact same name would be allowed. (Otherwise your code cannot know which one has been selected just by looking at the name.)
const CARS_BY_ID = {
ID_1: 'Ferrari',
ID_2: 'Lamborghini',
ID_3: 'Jeep',
}
class MyElem extends LitElement {
constructor() {
super();
this.carID = null;
}
render() {
return html`
<input list="myopts" #change=${this.carChanged}>
<datalist id="myopts">
${Object.values(CARS_BY_ID).map((name) => html`<option>${name}</option>`)}
</datalist>`;
}
carChanged(e) {
const name = e.target.value;
this.carID = null;
for (const [key, value] of Object.entries(CARS_BY_ID)) {
if (value === name) {
this.carID = key;
}
}
console.log(`this.carID = ${this.carID}`);
}
}
Note, that in this example the user can e.g. enter "Bugatti" and this.carID will be null.
Also note, that this.carID has not been registered as a lit-element property (it's not listed in static get properties), so there will be no update lifecycle triggered, and no re-rendering happens upon that change.

Select first element in dropdown in Angular 7

I am getting content of dropdown list as a Map<number, string>. When I get the map, it is received sorted according to keys in ascending order.
While showing it in html, I am setting pipe keyvalue and provided a function to sort the items in ascending order of values.
Now, I am trying to select first element of this dropdown, but unable to do so.
I have tried jQuery method to select the first element.
I have tried to set ngModel of the select box to first value of the map, but it sets the value to the first value received in the Map which is sorted by key.
My HTML:
<select class="form-control" id="empId" [(ngModel)]="empId" [disabled]="!isEditable">
<option *ngFor="let emp of empNames | keyvalue:descOrder" [value]="emp.key">{{ emp.value }}</option>
</select>
My ts file:
this.commonService.getEmployeeList())
.subscribe((response) => {
this.empNames = response;
this.empId = this.empNames.keys().next().value;
});
data I am sending from server is:
{id:1,name: "Tim"},
{id:6,name: "Martha"},
{id:5,name: "Alex"},
{id:8,name: "Stacy"}
data I am receiving on screen is like:
Alex
Martha
Stacy
Tim
with Tim pre-selected
what I need is Alex should be pre-selected.

Then set the empId before subscribing.
this.empId = 5;
this.commonService.getEmployeeList())
.subscribe((response) => {
this.empNames = response;
});
Of course you might want another logic based on some kind of order. You can never be sure how the data are going to be received.
In this case you need to send the order from your api and filter by order.

Working Demo
<option *ngFor="let emp of empNames | keyvalue:descOrder" [value]="emp.key" [selected]="emp.id === 1">{{ emp.value }}</option>
you can use selected attribute like above

I would highly recommand you to use Angular's reactive forms! And set the select's value to the one you want, when you recieve your data. Don't use ngModel as it is deprecated and should have been removed by Angular 7 (Or will be soon). Check this

The best way to pre select an option is to use ngModel as you tried. Your list is sorted by keys so what you want is not to select the first item, yes it's the first but in other order so or you change the order in code or you search for the item you want to select and stores it to set on model.
I would suggest some changes that should improve the code and fix your problem.
<select class="form-control" id="empId" [(ngModel)]="currentEmployer" [disabled]="!isEditable">
<option *ngFor="let emp of employers$ | async" [value]="emp">{{ emp.value }}</option>
</select>
And order your list in a pipe with the function you prefer.
public currentEmployer: Employer = null;
private sortByNameAscending(e1, e2) {
return e1.name > e2.name ? 1 : 0;
}
this.employers$ = this.commonService.getEmployeeList().pipe(
switchMap(employers => {
const sortedList = employers.sort(this.sortByNameAscending);
if (sortedList.length > 0) {
this.currentEmployer = sortedList[0];
}
return sortedList;
})
);

Get last clicked element in multiple select Angular

Im trying to get the last clicked option in a multiple select, no matters if the option is selected or unselected.
The problem is that the select is not via template, is mounted dinamically via TS.
I've tried adding vanilla JS event listeners at the creation of the options but doesn't works. Actually i can get all the selected elements, but i lost the unselected option and i can't get exactly the new selected one.
My HTML
<tr *ngFor="let communityLine of communityLines">
<td>{{communityLine.name}}</td>
<td>{{communityLine.instrument.name}}</td>
<td>{{communityLine.param.name}}</td>
<td>{{communityLine.contextSource.name}}</td>
<td>{{communityLine.sampleType.name}}</td>
<td>{{communityLine.value}}</td>
<td>
<select multiple [id] ="communityLine.apiKey" (change)="eventGetChange(communityLine, $event)" [(ngModel)]="nodeKey">
</select>
</td>
</tr>
My TS function
private eventGetChange(commLineKey, event) {
console.log(this.nodeKey);
console.log(commLineKey);
console.log(event.target.value)
My TS method to mount the select, is a bit complicated because i need to show all nodes (stored in this.allNodes var) but select the nodes that are in other array (nodesInRelation var).
private mountSelect(nodesInRelation: Node[], lineApiKey: String): void {
let select = <HTMLSelectElement>document.getElementById(lineApiKey);
let copy = this.allNodes;
for (let node of nodesInRelation) {
copy.forEach((item, index) => {
if (item.name === node.name) copy.splice(index, 1);
});
}
for (let node of nodesInRelation) {
let newoption = new Option(node.name, node.apiKey, null, true);
select.add(newoption);
}
for (let node of copy) {
let newoption = new Option(node.name, node.apiKey, null, false);
select.add(newoption);
}
M.updateTextFields();
M.AutoInit();
}
In eventGetChange function first console.log i get all the current selected values, in the second i get the key and is okey and in the third i get only the first selected element in the box.
I just want the last clicked, selected or unselected.
Thanks you.

You seem to be ditching Angular and opting for direct DOM manipulation for no apparent reason. Angular is perfectly capable of populating options list programmatically. It could look something like
<td>
<select multiple [id] ="communityLine.apiKey" [(ngModel)]="nodeKey">
<option *ngFor="let option of optionList; let i = index"
[value]="option" (click)="eventGetChange(option)">{{ option }}
</option>
</select>
</td>
optionList: any[];
private mountSelect(nodesInRelation: Node[], lineApiKey: String): void {
// populate optionList here
}
private eventGetChange(commLineKey) {
// the clicked option is available here
}

If this.nodeKey as you say stores an array with all the current selected values you can simply do this:
this.nodeKey[this.nodeKey.length - 1]
It will give you the las value in the nodeKey array

Dropdown list - model binding by value - angular 2

I have a page which allows a user to update the colour of a car. There are two api calls, one to bring back the car json object and one to fill a drop down list of colours.
My issue is that Angular 2 appears to do model binding via reference and not value. This means that although the colour 'green' might be set on the car, the color 'green' will not be selected in the drop down list even when it matches as that object has come from a different api call.
Here the select list is bound to the 'colour' property of car.
<div>
<label>Colour</label>
<div>
<select [(ngModel)]="car.colour">
<option *ngFor="let x of colours" [ngValue]="x">{{x.name}}</option>
</select>
</div>
</div>
When I set up the model in the back-end, if I set the color of the car to have the same value object (in this case green), the drop down is not selected. However when I set it using the same instance from the list of values used to bind the list it is selected as expected.
ngOnInit(): void {
this.colours = Array<Colour>();
this.colours.push(new Colour(-1, 'Please select'));
this.colours.push(new Colour(1, 'Green'));
this.colours.push(new Colour(2, 'Pink'));
this.car = new Car();
//this.car.colour = this.colours[1]; // Works
this.car.colour = new Colour(1, 'Green'); // Fails
}
Here is a plunker showing the issue. Simply switch between these to lines to illustrate the issue.
this.car.colour = this.colours[1]; // Works
this.car.colour = new Colour(1, 'Green'); // Fails
https://plnkr.co/edit/m3xBf8Hq9MnKiaZrjAaI?p=preview
How can I get angular to compare objects by value not reference when binding in this way?
Regards
Steve
Update
I solved in in my use case by setting the models 'superPower' property to the matching item in the list used to populate the dropdown list.
setupUpdate(id: number): void {
this.pageMode = PageMode.Update;
this.submitButtonText = "Update";
this.httpService.get<Hero>(this.appSettings.ApiEndPoint + 'hero/' + this.routeParams.get('id')).subscribe(response => {
this.hero = response;
this.httpService.get<SuperPower[]>(this.appSettings.ApiEndPoint + 'superPower/').subscribe(response => {
this.superPowers = response;
this.hero.superPower = this.superPowers.filter(x => x.id == this.hero.superPower.id)[0];
});
});
}

That's as designed. Angular2 only compares the object reference, not properties of an object.
You can bind to primitive values then compairson works as you expect
<select [(ngModel)]="car.colour.name">
<option *ngFor="let x of colours" [value]="x.name">{{x.name}}</option>
</select>
assuming that Color has a property name that contains the string Green.
You can also do the compairson yourself by looking up car.colour in colours and setting car.colour to the Colour instance from colours that represents the same colour.

You can use the following
<select [(ngModel)]="car.colour.name" (ngModelChange)="someFunction($event)" >
<option *ngFor="let x of colours" [value]="x.name">{{x.name}}</option>
</select>
When selected value would be updated, you will handle this in someFunction

Angular: Get the index of the dropdown item

I have the following in my view
<div>
<select ng-model="obj.arr[otherObj.variable]" ng-change="otherObj.variable=SOMETHING">
<option ng-repeat="label in obj.arrs">{{label}}</option>
</select>
</div>
Without the ng-change attribute, this code does what I want when otherObj.variable is one of the indexes of the obj.arr - it selects the correct item in the list.
What I want in addition to this is to set otherObj.variable to the index of the array item that is picked when the dropdown variable is changed. So, if the second value in the dropdown is picked then otherObj.variable should be set to 1. I tried to do this with a
ng-change="otherObj.variable=SOMETHING"
Problem is., I don't know what that SOMETHING should be. Am I doing this right?
EDIT
My requirements are
Select the top option in the dropdown by default
select the appropriate item in the array depending on the value of otherObj.variable (this gets set by some external code so if I come to the page with this value set then I want the correct option selected)
Make sure otherObj.variable is updated if I change the value in the dropdown.

angular.module('selects.demo', [])
.controller('SelectCtrl', function($scope){
$scope.values = [{
id: 1,
label: 'aLabel',
}, {
id: 2,
label: 'bLabel',
}];
$scope.selectedval = $scope.values[0];
});
<script src="https://code.angularjs.org/1.3.15/angular.js"></script>
<div ng-app="selects.demo">
<div ng-controller="SelectCtrl">
<p>Using ngOptions without select as:</p>
<select ng-model="selectedval" ng-options="value.label for value in values"></select>
<p>{{selectedval}}</p>
<p>Using ngOptions with select as statement: (this will return just the id in the model)</p>
<select ng-model="selectedval2" ng-options="value.id as value.label for value in values"></select>
<p>{{selectedval2}}</p>
</div>
</div>
Sorry if my comment was a little cryptic. Select elements like other form elements are actually directives in AngularJS, so they do a lot of stuff for you automatically. You don't need to use an ngChange to populate the ngModel associated with your select element. AngularJS will handle that for you.
Also, you can use ngOptions instead of ngRepeat on select elements to generate the values automatically on options.
Assuming that you have an object with values:
$scope.values = [{
id: 1,
label: 'aLabel',
}, {
id: 2,
label: 'bLabel',
}];
You would write:
<select ng-model="selectedval" ng-options="value.label for value in values"></select>
Now your ngModel is going to be bound to the selected element. It will be set with the value of the object that was chosen. If you add {{selectedval.id}} to your view, it will display the id of the selected element.
If you want to set the value to the first item, in your controller, you would add:
$scope.selectedval = $scope.values[0];
If you want to update some property on $scope.values based on the selected value, you could use something like:
$scope.addActiveProp = function() {
var selected = $scope.values.filter(function(e) { return e == $scope.selectedval; });
selected.active = true;
}
And then run the addActiveProp fn in ngChange on the select.

Please give a try with below code
<select ng-model="obj.arr[otherObj.variable]" ng-change="otherObj.variable=key" ng-options="key as value for (key , value) in obj.arrs"></select>