Expressions do not need to be surrounded by quotes when being bound to attributes and properties in templates, though stylistically you may want to enforce the presence of them or the absence of them.
This rule enforces the absence or presence of quotes around expressions in template bindings.
The following patterns are considered warnings:
/* eslint "lit/quoted-expressions": "error" */
html`<x-foo attr="${val}"></x-foo>`;
html`<x-foo .prop="${val}"></x-foo>`;
The following patterns are not warnings:
/* eslint "lit/quoted-expressions": "error" */
html`<x-foo attr=${val}></x-foo>`;
html`<x-foo prop=${val}></x-foo>`;
The following patterns are considered warnings:
/* eslint "lit/quoted-expressions": ["error", "always"] */
html`<x-foo attr=${val}></x-foo>`;
html`<x-foo .prop=${val}></x-foo>`;
The following patterns are not warnings:
/* eslint "lit/quoted-expressions": ["error", "always"] */
html`<x-foo attr="${val}"></x-foo>`;
html`<x-foo prop="${val}"></x-foo>`;
If you do not care whether there are surrounding quotes or not, do not use this rule.