What is the best way to limit the selection of checkboxes based on specific conditions?

Question

What is the best way to limit the selection of checkboxes based on specific conditions?

Using ngModel in Angular 5, I have the following Html:

<span *ngFor="let id of Ids">
  <input class="checkbox" type="checkbox" [(ngModel)]="strManyModel[id]"   (change)="setValue($event)" [value]="id">
 </span>

And here is the corresponding TypeScript:

setValue(e){
   if(selectedChkBox > 5){
    this.strManyModel[e.target.value] = false;
  }
}

I am trying to limit the number of checkboxes that can be selected to 5. Currently, once 5 are selected, any additional selections are allowed. However, I want to restrict checkbox selection after 5 have been checked. Users should only be able to select up to 5 checkboxes at a time. If they try to check another one after selecting 5, they must first uncheck one of their previous selections.

javascript angular typescript angular5

Answer 1

Answer №1

To add another class property, you can create a new one called:

public maxAllowedCheckboxes = 5;

Next, implement the following function:

public isCheckboxDisabled(): boolean {
  return Ids.length >= this.maxAllowedCheckboxes;
}

Finally, include the following template code:

<input class="checkbox" [disabled]="isCheckboxDisabled()" type="checkbox" [(ngModel)]="strManyModel[id]" (change)="setValue($event, i)" [value]="id">

Answer 2

To add another class property, you can create a new one called:

public maxAllowedCheckboxes = 5;

Next, implement the following function:

public isCheckboxDisabled(): boolean {
  return Ids.length >= this.maxAllowedCheckboxes;
}

Finally, include the following template code:

<input class="checkbox" [disabled]="isCheckboxDisabled()" type="checkbox" [(ngModel)]="strManyModel[id]" (change)="setValue($event, i)" [value]="id">

Answer 3

Answer №2

If I'm understanding correctly, you're looking to deactivate other checkboxes when 5 are selected and keep the unchecked ones disabled until the number of checked boxes is less than 5...

One way to achieve this is by storing objects in an array with a checked property to monitor their state. Additionally, introduce a new boolean variable and a "counter" to track the number of checked checkboxes. Disable the unchecked checkboxes and once the maximum of 5 checkboxes have been chosen:

<div *ngFor="let chk of checkBox; let i = index">
  <input [(ngModel)]="chk.checked" 
         type="checkbox" 
         [disabled]="!chk.checked && maxNo" 
         (change)="onChange($event.target.checked)">{{chk.name}}
</div>

The array should contain objects with a name and checked property. The change event will increment or decrement based on the checked checkboxes and toggle the boolean flag maxNo:

onChange(isChecked: boolean) {
  isChecked ? this.amt++ : this.amt--;
  this.maxNo = this.amt === 5 ? true : false;
}

Check out this StackBlitz for reference.

Answer 4

If I'm understanding correctly, you're looking to deactivate other checkboxes when 5 are selected and keep the unchecked ones disabled until the number of checked boxes is less than 5...

One way to achieve this is by storing objects in an array with a checked property to monitor their state. Additionally, introduce a new boolean variable and a "counter" to track the number of checked checkboxes. Disable the unchecked checkboxes and once the maximum of 5 checkboxes have been chosen:

<div *ngFor="let chk of checkBox; let i = index">
  <input [(ngModel)]="chk.checked" 
         type="checkbox" 
         [disabled]="!chk.checked && maxNo" 
         (change)="onChange($event.target.checked)">{{chk.name}}
</div>

The array should contain objects with a name and checked property. The change event will increment or decrement based on the checked checkboxes and toggle the boolean flag maxNo:

onChange(isChecked: boolean) {
  isChecked ? this.amt++ : this.amt--;
  this.maxNo = this.amt === 5 ? true : false;
}

Check out this StackBlitz for reference.

Answer 5

Answer №3

One potential solution could look like this:

 <div *ngFor="let itemId of itemIds; index as ind">
  <input class="checkbox" type="checkbox" [(ngModel)]="selectedItems[itemId]" (change)="updateValue($event, ind)" [value]="itemId">
</div>

updateValue(event, index){
  if(itemIds.length >= 5){
    selectedItems[index] = false;
  }
}

Answer 6

One potential solution could look like this:

 <div *ngFor="let itemId of itemIds; index as ind">
  <input class="checkbox" type="checkbox" [(ngModel)]="selectedItems[itemId]" (change)="updateValue($event, ind)" [value]="itemId">
</div>

updateValue(event, index){
  if(itemIds.length >= 5){
    selectedItems[index] = false;
  }
}

What is the best way to limit the selection of checkboxes based on specific conditions?

Answer №1

Answer №2

Answer №3

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