There are several ways of checking whether a string starts or ends with a certain string, such as string.indexOf('foo') === 0 or using regexes with /^foo/ or /foo$/. ES2015 introduced simpler alternatives named String#startsWith and String#endsWith. This rule enforces the use of those whenever possible.
/^bar/.test(foo);
/bar$/.test(foo);foo.startsWith('bar');
foo.endsWith('bar');