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Sashikumar Yadav
Sashikumar Yadav

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Centralizing SVG Handling in Angular Applications

#angular #webdev #javascript #programming

SVG icons are essential for modern web UIs, but managing them directly in templates becomes challenging as applications grow. This post demonstrates how we implemented a scalable approach to SVG management in DevsWhoRun Angular application using modern directives and TypeScript.

The Problem

Inline SVGs in templates lead to several issues:

<button><svg class="w-5 h-5" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M12 .297c-6.63 0-12 5.373-12 12 0 5.303 3.438..." fill="currentColor"></path></svg>
  Sign in with GitHub
</button>
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  • Template Bloat: SVG markup clutters templates
  • Duplication: Same SVGs repeated across components
  • Inconsistency: Inconsistent rendering
  • Maintenance: Updates require changes in multiple files

The Solution: A Centralized SVG Approach

Our solution consists of two key components:

  1. A TypeScript constants file for SVG definitions
  2. An Angular directive for dynamic SVG rendering

Step 1: Create the SVG Constants File 

// svg-icon-constants.ts
import { Icon } from "./types";

// Type-safe icon name constants
export const ICON_NAME = {
  google: 'google',
  github: 'github',
  sun: 'sun',
  moon: 'moon',
  smile: 'smile',
  discord: 'discord'
}

// SVG path data mapped to icon names
export const SVG_ICONS: { [key: Icon]: string } = {
  [ICON_NAME.google]: `<svg viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg">
    <path d="M12.48 10.92v3.28h7.84c-.24 1.84-.853 3.187-1.787 4.133-1.147 1.147-2.933 2.4-6.053 2.4-4.827 0-8.6-3.893-8.6-8.72s3.773-8.72 8.6-8.72c2.6 0 4.507 1.027 5.907 2.347l2.307-2.307C18.747 1.44 16.133 0 12.48 0 5.867 0 .307 5.387.307 12s5.56 12 12.173 12c3.573 0 6.267-1.173 8.373-3.36 2.16-2.16 2.84-5.213 2.84-7.667 0-.76-.053-1.467-.173-2.053H12.48z"></path>
  </svg>`,

  [ICON_NAME.github]: `<svg viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg">
    <path d="M12 .297c-6.63 0-12 5.373-12 12 0 5.303 3.438 9.8 8.205 11.385.6.113.82-.258.82-.577 0-.285-.01-1.04-.015-2.04-3.338.724-4.042-1.61-4.042-1.61C4.422 18.07 3.633 17.7 3.633 17.7c-1.087-.744.084-.729.084-.729 1.205.084 1.838 1.236 1.838 1.236 1.07 1.835 2.809 1.305 3.495.998.108-.776.417-1.305.76-1.605-2.665-.3-5.466-1.332-5.466-5.93 0-1.31.465-2.38 1.235-3.22-.135-.303-.54-1.523.105-3.176 0 0 1.005-.322 3.3 1.23.96-.267 1.98-.399 3-.405 1.02.006 2.04.138 3 .405 2.28-1.552 3.285-1.23 3.285-1.23.645 1.653.24 2.873.12 3.176.765.84 1.23 1.91 1.23 3.22 0 4.61-2.805 5.625-5.475 5.92.42.36.81 1.096.81 2.22 0 1.606-.015 2.896-.015 3.286 0 .315.21.69.825.57C20.565 22.092 24 17.592 24 12.297c0-6.627-5.373-12-12-12" fill="currentColor"></path>
  </svg>`
  // Additional icons omitted for brevity
};
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Step 2: Create the SVG Icon Directive 

// svg-icon.ts
import { Directive, ElementRef, inject, input, OnInit, Renderer2 } from '@angular/core';
import { SVG_ICONS } from './svg-icon-constants';
import { Icon } from './types';

@Directive({
  selector: '[appSvgIcon]',
})
export class SvgIcon implements OnInit {
  // Modern Angular signals-based inputs
  iconName = input<Icon>('google');
  iconClass = input<string>('');
  fill = input<string>('currentColor');

  // Dependency injection using inject function
  private readonly el = inject(ElementRef);
  private readonly renderer = inject(Renderer2);

  ngOnInit(): void {
    if (!this.iconName() || !SVG_ICONS[this.iconName()]) {
      console.error(`SVG icon not found: ${this.iconName()}`);
      return;
    }

    const svgString = SVG_ICONS[this.iconName()];
    const parser = new DOMParser();
    const doc = parser.parseFromString(svgString, 'image/svg+xml');
    const svgElement = doc.documentElement;

    // Add CSS classes if provided
    if (this.iconClass()) {const classes = this.iconClass().split(' ');
      classes.forEach(className => {
        if (className) {
          this.renderer.addClass(svgElement, className);
        }
      });
    }

    // Set fill color for all paths
    const paths = svgElement.querySelectorAll('path');
    paths.forEach(path => {
      path.setAttribute('fill', this.fill());
    });

    // Append the SVG to the host element
    this.renderer.setProperty(this.el.nativeElement, 'innerHTML','');
    this.renderer.appendChild(this.el.nativeElement, svgElement);
  }
}
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Step 3: Create Type Definitions 

// types.ts
import { ICON_NAME } from "./svg-icon-constants";

// Creates a union type of all icon name values
export type Icon = (typeof ICON_NAME)[keyof typeof ICON_NAME];
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Step 4: Using the SVG Directive in Components

Implement the directive in any component:

// footer.ts
import { Component } from '@angular/core';
import { SvgIcon } from '../../../shared/directives/svg/svg-icon';
import { ICON_NAME } from '../../../shared/directives/svg/svg-icon-constants';

@Component({
  selector: 'app-footer',
  imports: [SvgIcon],
  template: `
    <footer class="bg-gray-800 text-white py-8">
      <div class="container mx-auto">
        <div class="flex justify-center space-x-6">
          <a href="https://github.com/yshashi/devswhomove" target="_blank" rel="noopener noreferrer">
            <span appSvgIcon [iconName]="iconName.github" iconClass="w-6 h-6"></span>
          </a>
          <a href="https://discord.gg/devswhomove" target="_blank" rel="noopener noreferrer">
            <span appSvgIcon [iconName]="iconName.discord" iconClass="w-6 h-6"></span>
          </a>
        </div>
        <p class="text-center mt-4">© 2025 DevsWhoMove. All rights reserved.</p>
      </div>
    </footer>
  `,
  standalone: true
})
export class Footer {
  protected readonly iconName = ICON_NAME;
}
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Technical Benefits

1. Clean, Type-Safe Templates

Before:

<a href="https://github.com/yshashi/devswhomove" target="_blank">
   <svg class="w-6 h-6" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M12 .297c-6.63 0-12 5.373-    12 12 0 5.303 3.438 9.8 8.205 11.385..." fill="currentColor"></path>
   </svg>
</a>
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After:

<a href="https://github.com/yshashi/devswhomove" target="_blank">
   <span appSvgIcon [iconName]="iconName.github" iconClass="w-6 h-6"></span>
</a>
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2. Developer Experience Improvements

  • Type Safety: TypeScript interfaces ensure correct icon names
  • Centralized Management: Single source of truth for all SVGs
  • IDE Support: Autocomplete for icon names and properties
  • Consistent Styling: Apply classes uniformly across all icons

3. Performance Optimizations

  • Reduced Bundle Size: No duplicate SVG definitions
  • Efficient DOM Operations: Directive handles optimal rendering
  • Caching: Browser can cache SVG content

Advanced Implementation Options

1. Server-Side Rendering Support

For Angular Universal applications, ensure the directive works with SSR by checking the platform before performing DOM operations:

import { PLATFORM_ID, inject } from '@angular/core';
import { isPlatformBrowser } from '@angular/common';

// Modern dependency injection
private readonly platformId = inject(PLATFORM_ID);

ngOnInit(): void {
  // Only perform DOM operations in browser environment
  if (isPlatformBrowser(this.platformId)) {
     // SVG parsing and DOM manipulation code
     const svgString = SVG_ICONS[this.iconName()];
     const parser = new DOMParser();
     // Rest of the implementation...
  }
}
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2. Lazy Loading Icons by Feature

For applications with many icons, implement lazy loading by feature using modern Angular patterns:

// feature-icons.ts
import { InjectionToken } from '@angular/core';

// Create a token for feature-specific icons
export const FEATURE_ICONS = new InjectionToken<Record<string, string>>('FEATURE_ICONS');

// Define feature-specific icons
export const DASHBOARD_ICONS = {
  chart: `<svg viewBox="0 0 24 24">...</svg>`,
  analytics: `<svg viewBox="0 0 24 24">...</svg>`
};

// In your feature module or component providers
providers: [
  {
    provide: FEATURE_ICONS,
    useValue: DASHBOARD_ICONS
  }
]

// Inject in directive
const featureIcons = inject(FEATURE_ICONS, { optional: true });

// Merge with core icons
const allIcons = { ...SVG_ICONS, ...featureIcons };
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Conclusion

Our centralized SVG handling approach in the DevsWhoRun Angular application demonstrates how modern Angular features like signals and functional dependency injection can create a clean, maintainable solution. By centralizing SVG definitions and using a directive for rendering, we've achieved:

  1. Improved Developer Experience: Type-safe icon references with IDE autocompletion
  2. Better Performance: Reduced bundle size and optimized rendering
  3. Enhanced Maintainability: Single source of truth for all SVG assets
  4. Flexible Styling: Dynamic class application and fill color control

This pattern scales well from small applications to enterprise-level projects, providing a solid foundation for consistent icon usage across your Angular applications.

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