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Avoid Self-Assignment of Variables

High
MaintainabilityCorrectness

What is it?​

Self-assignment occurs when a variable is assigned to itself, which serves no practical purpose. This often indicates redundant code or a potential error where a different variable or value was intended for assignment.

Why apply it?​

Removing self-assignment improves code clarity and maintainability. It prevents confusion for future readers and avoids unnecessary operations that might hide logic mistakes.

How to Fix it?​

Review your code to ensure that every assignment serves a clear purpose. Either remove the redundant self-assignment or assign the intended value to the appropriate variable or object property to correctly update the state.

Examples​

Example 1:​

Positive​

Correct implementation following the practice.

class User {
  name: string;

  updateName(name: string): void {
    console.log("Attempting to update user name");
    // Correct: Assign the value to the object's property instead of self-assignment.
    this.name = name;
    console.log(`User name is now set to: ${this.name}`);
    // Additional logic could follow here.
    console.log("Update complete.");
  }
}

const user = new User();
user.updateName("Alice");

Negative​

Incorrect implementation that violates the practice.

class User {
  name: string;

  updateName(name: string): void {
    console.log("Attempting to update user name");
    // Noncompliant: The parameter is redundantly assigned to itself.
    name = name;
    console.log(`After self-assignment, name is: ${name}`);
    // Other operations continue even though no actual update occurred.
    console.log("Update complete.");
  }
}

const user = new User();
user.updateName("Alice");

Example 2:​

Positive​

Correct implementation following the practice.

class Person {
  id: number;

  setId(id: number): void {
    console.log("Starting update for id");
    // Correct: The object's property is updated with the parameter value.
    this.id = id;
    console.log(`The object id is now ${this.id}`);
    // Additional business logic can proceed here.
    console.log("Update process complete.");
  }
}

const person = new Person();
person.setId(42);

Negative​

Incorrect implementation that violates the practice.

class Person {
  id: number;

  setId(id: number): void {
    console.log("Starting update for id");
    // Noncompliant: The parameter is redundantly assigned to itself.
    id = id;
    console.log(`The provided id remains ${id} without updating the object property`);
    // Additional logic that falsely assumes the id has been updated.
    console.log("Update process complete.");
  }
}

const person = new Person();
person.setId(42);