demo/typescript.js
function getTokenAtPositionWorker(sourceFile, position, allowPositionInLeadingTrivia, includeItemAtEndPosition) {
        var current = sourceFile;
        outer: while (true) {
            if (isToken(current)) {
                // exit early
                return current;
            }
            // find the child that contains 'position'
            for (var i = 0, n = current.getChildCount(sourceFile); i < n; i++) {
                var child = current.getChildAt(i);
                var start = allowPositionInLeadingTrivia ? child.getFullStart() : child.getStart(sourceFile);
                if (start <= position) {
                    var end = child.getEnd();
                    if (position < end || (position === end && child.kind === 1 /* EndOfFileToken */)) {
                        current = child;
                        continue outer;
                    }
                    else if (includeItemAtEndPosition && end === position) {
                        var previousToken = findPrecedingToken(position, sourceFile, child);
                        if (previousToken && includeItemAtEndPosition(previousToken)) {
                            return previousToken;
                        }
                    }
                }
            }
            return current;
        }
    }
function getTokenAtPositionWorker(sourceFile, position, allowPositionInLeadingTrivia, includeItemAtEndPosition) {
        var current = sourceFile;
        outer: while (true) {
            if (isToken(current)) {
                // exit early
                return current;
            }
            // find the child that contains 'position'
            for (var i = 0, n = current.getChildCount(sourceFile); i < n; i++) {
                var child = current.getChildAt(i);
                var start = allowPositionInLeadingTrivia ? child.getFullStart() : child.getStart(sourceFile);
                if (start <= position) {
                    var end = child.getEnd();
                    if (position < end || (position === end && child.kind === 1 /* EndOfFileToken */)) {
                        current = child;
                        continue outer;
                    }
                    else if (includeItemAtEndPosition && end === position) {
                        var previousToken = findPrecedingToken(position, sourceFile, child);
                        if (previousToken && includeItemAtEndPosition(previousToken)) {
                            return previousToken;
                        }
                    }
                }
            }
            return current;
        }
    }
Get the token whose text contains the position