lib/rules/keyword-spacing.js
function checkSpacingBeforeFirstToken(node) {
            const firstToken = node && sourceCode.getFirstToken(node);

            if (firstToken && firstToken.type === "Keyword") {
                checkSpacingBefore(firstToken);
            }
        }
function checkSpacingBeforeFirstToken(node) {
            const firstToken = node && sourceCode.getFirstToken(node);

            if (firstToken && firstToken.type === "Keyword") {
                checkSpacingBefore(firstToken);
            }
        }
function checkSpacingBeforeFirstToken ( node ) { const firstToken = node && sourceCode . getFirstToken ( node ) ; if ( firstToken && firstToken . type === "Keyword" ) { checkSpacingBefore ( firstToken ) ; } }
Reports the first token of a given node if the first token is a keyword
and usage of spacing followed by the token is invalid.

This is used for unary operators (e.g. `typeof`), `function`, and `super`.
Other rules are handling usage of spacing preceded by those keywords.

@param {ASTNode|null} node - A node to report.
@returns {void}
Reports the first token of a given node if the first token is a keyword and usage of spacing followed by the token is invalid .