typescript 58 lines · 10 steps

Building a signup stepper in Angular

A standalone Angular component pairs signals with a nested reactive form to drive a multi-step signup wizard.

Explained by highlit

Angular Intermediate signals reactive-forms form-validation state-management wizard

1import { Component, computed, inject, signal } from '@angular/core';
2import { FormBuilder, ReactiveFormsModule, Validators } from '@angular/forms';
3import { CommonModule } from '@angular/common';
4 
5@Component({
selector: 'app-signup-stepper',
standalone: true,
imports: [CommonModule, ReactiveFormsModule],
templateUrl: './signup-stepper.component.html',
10})
11export class SignupStepperComponent {
private fb = inject(FormBuilder);
13 
readonly steps = ['account', 'profile', 'billing'] as const;
readonly currentStep = signal(0);
16 
readonly form = this.fb.group({
  account: this.fb.group({
    email: ['', [Validators.required, Validators.email]],
    password: ['', [Validators.required, Validators.minLength(8)]],
  }),
  profile: this.fb.group({
    firstName: ['', Validators.required],
    lastName: ['', Validators.required],
  }),
  billing: this.fb.group({
    cardNumber: ['', [Validators.required, Validators.pattern(/^\d{16}$/)]],
    cvc: ['', [Validators.required, Validators.pattern(/^\d{3}$/)]],
  }),
});
31 
readonly isLastStep = computed(() => this.currentStep() === this.steps.length - 1);
33 
private activeGroup() {
  return this.form.get(this.steps[this.currentStep()])!;
}
37 
next(): void {
  const group = this.activeGroup();
  if (group.invalid) {
    group.markAllAsTouched();
    return;
  }
  if (!this.isLastStep()) {
    this.currentStep.update((i) => i + 1);
  }
}
48 
back(): void {
  this.currentStep.update((i) => Math.max(0, i - 1));
}
52 
submit(): void {
  if (this.form.valid) {
    this.form.disable();
  }
}
58}

01 / 01

STEP 01

Walkthrough

Space play ←→ step click any line

Three takeaways

1Nesting form groups by step lets you validate one section at a time while keeping a single source of truth.
2Angular signals model wizard state declaratively, so derived facts like the last step recompute automatically.
3Gating step advancement on per-group validity gives users focused feedback instead of a wall of errors.

Related explainers

javascript

import { useReducer, useCallback } from 'react';
 
function historyReducer(state, action) {
  const { past, present, future } = state;

Undo/redo form state with a React reducer

undo-redo reducer immutability

Intermediate 10 steps

typescript

type Middleware<TIn, TOut> = (ctx: TIn) => Promise<TOut> | TOut;
 
class Pipeline<TIn, TOut> {
  private constructor(private readonly run: Middleware<TIn, TOut>) {}

A type-safe async middleware pipeline

generics type-safety middleware

Advanced 9 steps

typescript

type Countdown = {
  days: number;
  hours: number;
  minutes: number;

Building a self-stopping countdown timer

date-math closures timers

Intermediate 9 steps

python

from django.core.cache import cache
from django.core.cache.utils import make_template_fragment_key
from django.db.models.signals import post_save, post_delete
from django.dispatch import receiver

Busting template fragment caches in Django

caching signals cache-invalidation

Intermediate 4 steps

typescript

export function isValidCardNumber(input: string): boolean {
  const digits = input.replace(/[\s-]/g, "");
 
  if (!/^\d{12,19}$/.test(digits)) {

Validating card numbers with the Luhn check

luhn-algorithm checksum input-validation

Intermediate 7 steps

typescript

interface UserAgentInfo {
  browser: { name: string; version: string };
  os: { name: string; version: string };
  device: 'mobile' | 'tablet' | 'desktop';