lib/rules/keyword-spacing.js
function checkSpacingBefore(token, pattern) {
            checkMethodMap[token.value].before(token, pattern || PREV_TOKEN);
        }
function checkSpacingBefore(token, pattern) {
            checkMethodMap[token.value].before(token, pattern || PREV_TOKEN);
        }
function checkSpacingBefore ( token , pattern ) { checkMethodMap [ token . value ] . before ( token , pattern || PREV_TOKEN ) ; }
Reports a given token if usage of spacing followed by the token is
invalid.

@param {Token} token - A token to report.
@param {RegExp|undefined} pattern - Optional. A pattern of the previous
token to check.
@returns {void}
Reports a given token if usage of spacing followed by the token is invalid .