TS2683: this implicitly has type any

Arrow functions capture 'this' from the surrounding context.

class Counter {
  count = 0

  // ❌ Regular function loses this context
  startBad() {
    setInterval(function() {
      this.count++  // TS2683: this implicitly has type any
    }, 1000)
  }

  // ✅ Arrow function preserves this
  startGood() {
    setInterval(() => {
      this.count++  // ✅ Correctly typed
    }, 1000)
  }
}

Use .bind() to bind the correct this context to a function.

class Logger {
  prefix = "[App]"

  log(message: string) {
    console.log(`${this.prefix}: ${message}`)
  }

  setup() {
    // ❌ Loses this when passed as callback
    button.addEventListener("click", this.log)

    // ✅ Bind this explicitly
    button.addEventListener("click", this.log.bind(this))

    // ✅ Or wrap in arrow function
    button.addEventListener("click", (e) => this.log("clicked"))
  }
}

Use the this parameter to declare the expected this type.

// Type the this parameter explicitly
function handleClick(this: HTMLButtonElement, event: MouseEvent) {
  this.disabled = true  // ✅ this is typed as HTMLButtonElement
}

button.addEventListener("click", handleClick)

// For object methods with explicit this
interface User {
  name: string
  greet(this: User): string
}

const user: User = {
  name: "Alice",
  greet(this: User) {
    return `Hello, ${this.name}`
  }
}