Selecting an option with a specific index in Angular 2 RC2

Question

Selecting an option with a specific index in Angular 2 RC2

I have encountered a situation where the select options are non-unique, with the same value representing different things. This is how our data is structured and I need to work within those constraints.

<select id="mySelect">
  <option value = "1">Apple</option>
  <option value = "2">Orange</option>
  <option value = "3">Pineapple</option>
  <option value = "1">Banana</option>
</select>

In order to set the value based on index, I can use the selectedIndex property.

document.getElementById("mySelect").selectedIndex = 3;

However, when using Angular 2, I encounter an error stating "Property 'selectedIndex' does not exist on type 'HTMLElement'. any".

How can I retrieve selectedIndex in Angular 2 or find a workaround for this issue?

Update: I am attempting to set a default value for the select option based on other data retrieved from the database. The scenario is as follows:

this.data$.subscribe(data => {
    this.data = data; 
    if (data.someConditionMet) { 
      document.getElementById("mySelect").selectedIndex = 3;
    }
}, 
error =>  this.errorMessage = <any>error);

It is important to note that while the values in the options may be duplicate, the entries themselves are unique. For example, value "1" could represent either "Apple" or "Banana". This is why I prefer using index over value.

typescript angular

Answer 1

Answer №1

Typically, the best practice in Angular 2 is to let your data control the dom instead of the other way around.

An example implementation could look like this:

<select id="mySelect">
  <option *ngFor="let dataValue of myDataArray" value = "dataValue.value" (click)="onSelected(dataValue)">{{dataValue.Text}}</option>
</select>

You would then have a onSelected handler in your component that can identify which data item was selected.

If you need a default selection based on your data, simply add

[selected]="someJavascriptExpression"

to the option element. For example:

[selected]="dataValue.value === someCond && dataValue.text === someOtherCond"

. This ensures each option element is uniquely selected based on your data.

Answer 2

Typically, the best practice in Angular 2 is to let your data control the dom instead of the other way around.

An example implementation could look like this:

<select id="mySelect">
  <option *ngFor="let dataValue of myDataArray" value = "dataValue.value" (click)="onSelected(dataValue)">{{dataValue.Text}}</option>
</select>

You would then have a onSelected handler in your component that can identify which data item was selected.

If you need a default selection based on your data, simply add

[selected]="someJavascriptExpression"

to the option element. For example:

[selected]="dataValue.value === someCond && dataValue.text === someOtherCond"

. This ensures each option element is uniquely selected based on your data.

Answer 3

Answer №2

To easily set or retrieve the current value, utilize the select model:

<select id="mySelect" [(ngModel)]="selectedValue">
  <option *ngFor="let dataValue of myDataArray" 
           value="dataValue.value" 
           (click)="onSelected(dataValue)">
    {{dataValue.Text}}
  </option>
</select>

In your component file:

export class ComponentA {
    selectedValue: number = -1;

    // ...

    this.data$.subscribe(data => {
            this.data = data; 
            if (data.someConditionMet) { 
                selectedValue = 3;
            }
        }, 
        error =>  this.errorMessage = <any>error
    );

Answer 4

To easily set or retrieve the current value, utilize the select model:

<select id="mySelect" [(ngModel)]="selectedValue">
  <option *ngFor="let dataValue of myDataArray" 
           value="dataValue.value" 
           (click)="onSelected(dataValue)">
    {{dataValue.Text}}
  </option>
</select>

In your component file:

export class ComponentA {
    selectedValue: number = -1;

    // ...

    this.data$.subscribe(data => {
            this.data = data; 
            if (data.someConditionMet) { 
                selectedValue = 3;
            }
        }, 
        error =>  this.errorMessage = <any>error
    );

Answer 5

Answer №3

Utilize the $event.target.selectedIndex property and set selIdx to 0. After that,

<select (change)="selIdx = $event.target.selectedIndex;"> Select One
   <option *ngFor="let a of array; let i = index;" value="{{ a.val }}" [selected]="selIdx == i">
      {{ a.desc }}
   </option>
</select>

Answer 6

Utilize the $event.target.selectedIndex property and set selIdx to 0. After that,

<select (change)="selIdx = $event.target.selectedIndex;"> Select One
   <option *ngFor="let a of array; let i = index;" value="{{ a.val }}" [selected]="selIdx == i">
      {{ a.desc }}
   </option>
</select>

Answer 7

Answer №4

Stumbled upon an interesting discovery.

In cases where select options are not unique, Angular2 automatically adjusts the values by adding an index. For instance, from

<select id="mySelect">
  <option value = "1">Apple</option>
  <option value = "2">Orange</option>
  <option value = "3">Pineapple</option>
  <option value = "1">Banana</option>
</select>

to

<select id="mySelect">
  <option value = "0: 1">Apple</option>
  <option value = "1: 2">Orange</option>
  <option value = "2: 3">Pineapple</option>
  <option value = "3: 1">Banana</option>
</select>

Hence, within my code, I can simply write

this.data$.subscribe(data => {
    this.data = data; 
    if (data.someConditionMetForBanana) { 
      ngModelBoundSelectedValue = "3: 1";
    }
}, 
error =>  this.errorMessage = <any>error);

hholtij's comment was accurate. It's indeed a handy feature that Angular2 provides for us.

Answer 8

Stumbled upon an interesting discovery.

In cases where select options are not unique, Angular2 automatically adjusts the values by adding an index. For instance, from

<select id="mySelect">
  <option value = "1">Apple</option>
  <option value = "2">Orange</option>
  <option value = "3">Pineapple</option>
  <option value = "1">Banana</option>
</select>

to

<select id="mySelect">
  <option value = "0: 1">Apple</option>
  <option value = "1: 2">Orange</option>
  <option value = "2: 3">Pineapple</option>
  <option value = "3: 1">Banana</option>
</select>

Hence, within my code, I can simply write

this.data$.subscribe(data => {
    this.data = data; 
    if (data.someConditionMetForBanana) { 
      ngModelBoundSelectedValue = "3: 1";
    }
}, 
error =>  this.errorMessage = <any>error);

hholtij's comment was accurate. It's indeed a handy feature that Angular2 provides for us.

Selecting an option with a specific index in Angular 2 RC2

Answer №1

Answer №2

Answer №3

Answer №4

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