no-property-change-update.md

Disallows property changes in the update lifecycle method after a super call (no-property-change-update)

Property changes in the update lifecycle method will not trigger a re-render unless super.update is called after the changes.

Rule Details

This rule disallows assigning to observed properties in the update method after super.update has been called.

The following patterns are considered warnings:

static get properties() {
  return { prop: { type: Number } };
}
update() {
  super.update();
  this.prop = 5;
}

The following patterns are not warnings:

class A extends LitElement {
  static get properties() {
    return {};
  }
  update() {
    this.unobserved = 5;
  }
}

class B extends LitElement {
  static get properties() {
    return { prop: { type: Number } };
  }
  update() {
    this.prop = 5;
    super.update();
  }
}

When Not To Use It

If you are aware of the fact a render won't happen in these cases but still wish to mutate the properties, you should not use this rule.