Paste Cleanup in Angular Block Editor

The Block Editor component provides robust paste clean-up functionalities to ensure that pasted content integrates seamlessly and maintains styling and structural consistency. This feature helps remove unwanted formatting, scripts, and elements copied from external sources like web pages or word processors.

You can configure the paste behavior using the pasteCleanupSettings property, which allows you to define how content is handled when pasted into the editor.

Configuring allowed styles

The allowedStyles property lets you define which CSS styles are permitted in pasted content. Any style not in this list is stripped out, ensuring that only desired visual attributes are preserved.

By default, the following styles are allowed: font-weight, font-style, text-decoration, and text-transform.

In the following example, only font-weight and font-style are retained from the pasted content. All other inline styles are removed:

import { Component } from '@angular/core';
import { BlockEditorModule } from '@syncfusion/ej2-angular-blockeditor';
import { PasteCleanupSettingsModel } from '@syncfusion/ej2-blockeditor';

@Component({
    imports: [BlockEditorModule],
    standalone: true,
    selector: 'app-root',
    template: `
        <div class="container" style="margin: 50px;">
            <ejs-blockeditor [pasteCleanupSettings]="pasteCleanupSettings" />
        </div>`
})
export class AppComponent {
    public pasteCleanupSettings: PasteCleanupSettingsModel = {
        allowedStyles: ['font-weight', 'font-style']
    };
}

Setting denied tags

The deniedTags property specifies a list of HTML tags to be removed from pasted content. This is useful for stripping potentially problematic elements such as <script> or <iframe> tags. By default, this property is an empty array, so no tags are removed.

In the following example, any <script> or <iframe> tags found in the pasted content are removed, preventing unwanted behavior or styling issues:

import { Component } from '@angular/core';
import { BlockEditorModule } from '@syncfusion/ej2-angular-blockeditor';
import { PasteCleanupSettingsModel } from '@syncfusion/ej2-blockeditor';

@Component({
    imports: [BlockEditorModule],
    standalone: true,
    selector: 'app-root',
    template: `
        <div class="container" style="margin: 50px;">
            <ejs-blockeditor [pasteCleanupSettings]="pasteCleanupSettings" />
        </div>`
})
export class AppComponent {
    public pasteCleanupSettings: PasteCleanupSettingsModel = {
        deniedTags: ['script', 'iframe']
    };
}

The example below demonstrates the usage of paste settings that allow only specific styles and also remove specific tags from the pasted content.

import { Component } from '@angular/core';
import { BlockEditorModule } from "@syncfusion/ej2-angular-blockeditor";
import { BlockModel, AfterPasteCleanupEventArgs } from "@syncfusion/ej2-blockeditor";

@Component({
    imports: [BlockEditorModule],
    standalone: true,
    selector: 'app-root',
    templateUrl: './app.component.html'
})

// Initialize BlockEditor with paste cleanup settings
export class AppComponent {
    public output = '';
    public blockData: BlockModel[] = [
        {
            blockType: 'Paragraph'
        }
    ];
    // Configure paste cleanup settings
    public pasteCleanupSettings = {
        allowedStyles: ['text-decoration'],
        deniedTags: ['script', 'iframe']
    };
    public handleAfterPaste = (args: AfterPasteCleanupEventArgs) => {
        this.displayOutput(`After Paste Event: Processed content length: ${args.content.length} characters`);
    }

    ngOnInit(): void {
        this.displayOutput(`Paste Cleanup Settings Active:
        - Allowed Styles: ['text-decoration']
        - Denied Tags: ['script', 'iframe']

        Copy content from the test area above and paste it into the editor to see the cleanup in action.`);
    }

    // Output helper function
    displayOutput(message: string): void {
        this.output = message;
    }

}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
bootstrapApplication(AppComponent).catch((err) => console.error(err));
<div id="container">
    <ejs-blockeditor id="blockeditor" [blocks]="blockData" [pasteCleanupSettings]="pasteCleanupSettings" (afterPasteCleanup)="handleAfterPaste($event)" />
    <div id="controls">
        <h4>Test Content to Copy and Paste:</h4>
        <div class="test-content">
            <div id="sampleContent" contenteditable="true">
                <h2 style="color: red; font-weight: bold; font-size: 24px;">Formatted Heading</h2>
                <p style="background-color: yellow; font-style: italic;">
                    This is a <span style="font-weight: bold;">bold paragraph</span> with 
                    <span style="color: blue; font-style: italic;">italic text</span> and 
                    <span style="text-decoration: underline;">underlined content</span>.
                </p>
                <script> console.log('This script should be removed'); </script>
                <iframe src="about:blank" width="100" height="50"></iframe>
                <div style="border: 1px solid black; padding: 10px;">
                    <span style="font-weight: 600;">Heavy text</span> and 
                    <span style="color: green; font-size: 18px;">colored text</span>
                </div>
            </div>
        </div>
        <div id="output"></div>
    </div>
</div>

Disable keep format

By default, the editor retains the formatting of pasted content (for example, bold, italics, links). You can disable this by setting the keepFormat property to false. When disabled, the editor pastes content as plain text, regardless of the allowedStyles configuration:

import { Component } from '@angular/core';
import { BlockEditorModule } from '@syncfusion/ej2-angular-blockeditor';
import { PasteCleanupSettingsModel } from '@syncfusion/ej2-blockeditor';

@Component({
    imports: [BlockEditorModule],
    standalone: true,
    selector: 'app-root',
    template: `
        <div class="container" style="margin: 50px;">
            <ejs-blockeditor [pasteCleanupSettings]="pasteCleanupSettings" />
        </div>`
})
export class AppComponent {
    public pasteCleanupSettings: PasteCleanupSettingsModel = {
        keepFormat: false
    };
}

Allow plain text

To paste content as plain text, stripping all HTML tags and inline styles, set the plainText property to true in pasteCleanupSettings. This ensures that only raw text is inserted, which is ideal for maintaining strict content consistency. By default, this property is false.

import { Component } from '@angular/core';
import { BlockEditorModule } from '@syncfusion/ej2-angular-blockeditor';
import { PasteCleanupSettingsModel } from '@syncfusion/ej2-blockeditor';

@Component({
    imports: [BlockEditorModule],
    standalone: true,
    selector: 'app-root',
    template: `
        <div class="container" style="margin: 50px;">
            <ejs-blockeditor [pasteCleanupSettings]="pasteCleanupSettings" />
        </div>`
})
export class AppComponent {
    public pasteCleanupSettings: PasteCleanupSettingsModel = {
        plainText: true
    };
}

The example below demonstrates the usage of paste settings that disable keep format and allow plain text.

import { Component } from '@angular/core';
import { BlockEditorModule } from "@syncfusion/ej2-angular-blockeditor";
import { BlockModel, AfterPasteCleanupEventArgs } from "@syncfusion/ej2-blockeditor";

@Component({
    imports: [BlockEditorModule],
    standalone: true,
    selector: 'app-root',
    templateUrl: './app.component.html'
})

// Initialize BlockEditor with paste cleanup settings
export class AppComponent {
    public output = '';
    public blockData: BlockModel[] = [
        {
            blockType: 'Paragraph'
        }
    ];
    // Configure paste cleanup settings
    public pasteCleanupSettings = {
        keepFormat: false,
        plainText: true
    };
    public handleAfterPaste = (args: AfterPasteCleanupEventArgs) => {
        this.displayOutput(`After Paste Event: Processed content length: ${args.content.length} characters`);
    }

    ngOnInit(): void {
       this.displayOutput(`Paste Cleanup Settings Active:
        - Keep Format: false
        - Plain Text: true

        Copy content from the test area above and paste it into the editor to see the cleanup in action.`);
    }

    // Output helper function
    displayOutput(message: string): void {
        this.output = message;
    }

}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
bootstrapApplication(AppComponent).catch((err) => console.error(err));
<div id="container">
    <ejs-blockeditor id="blockeditor" [blocks]="blockData" [pasteCleanupSettings]="pasteCleanupSettings" (afterPasteCleanup)="handleAfterPaste($event)" />
    <div id="controls">
        <h4>Test Content to Copy and Paste:</h4>
        <div class="test-content">
            <div id="sampleContent" contenteditable="true">
                <h2 style="color: red; font-weight: bold; font-size: 24px;">Formatted Heading</h2>
                <p style="background-color: yellow; font-style: italic;">
                    This is a <span style="font-weight: bold;">bold paragraph</span> with 
                    <span style="color: blue; font-style: italic;">italic text</span> and 
                    <span style="text-decoration: underline;">underlined content</span>.
                </p>
                <div style="border: 1px solid black; padding: 10px;">
                    <span style="font-weight: 600;">Heavy text</span> and 
                    <span style="color: green; font-size: 18px;">colored text</span>
                </div>
            </div>
        </div>
        <div id="output"></div>
    </div>
</div>

Events

The Block Editor provides events to monitor and interact with the paste action:

Event Args Description
beforePasteCleanup BeforePasteCleanupEventArgs Triggers before the content is pasted into the editor.
afterPasteCleanup AfterPasteCleanupEventArgs Triggers after the content has been pasted into the editor.

Bind the events on the editor element and pass $event to your handler if you want to inspect the args:

<ejs-blockeditor
    (beforePasteCleanup)="onBeforePasteCleanup($event)"
    (afterPasteCleanup)="onAfterPasteCleanup($event)" />
import { BeforePasteCleanupEventArgs, AfterPasteCleanupEventArgs } from '@syncfusion/ej2-blockeditor';

public onBeforePasteCleanup(args: BeforePasteCleanupEventArgs): void {
    // Inspect or rewrite args.blocks before they are inserted.
}

public onAfterPasteCleanup(args: AfterPasteCleanupEventArgs): void {
    // React to the inserted content, e.g. log the paste for analytics.
}