Can JavaScript Object Property Name Have Underscores?

JavaScript object property names can be any string, including having underscores in the name. In fact, underscores are valid identifiers, which means that:

• Property names can be specified without quotes;
• Properties can be accessed using either the dot notation (i.e. object.property syntax) or the bracket notation (i.e. object['property'] syntax).

For example, the following is a valid property name:

const obj = { foo_bar: 'baz' };

console.log(obj.foo_bar); // 'baz'
console.log(obj['foo_bar']); // 'baz'

You can even have underscores at start or the end of the property name:

const obj = { _foo_: 'bar' };

console.log(obj._foo_); // 'bar'
console.log(obj['_foo_']); // 'bar'