demo/typescript.js
function prepareRangeContainsErrorFunction(errors, originalRange) {
            if (!errors.length) {
                return rangeHasNoErrors;
            }
            // pick only errors that fall in range
            var sorted = errors
                .filter(function (d) { return ts.rangeOverlapsWithStartEnd(originalRange, d.start, d.start + d.length); })
                .sort(function (e1, e2) { return e1.start - e2.start; });
            if (!sorted.length) {
                return rangeHasNoErrors;
            }
            var index = 0;
            return function (r) {
                // in current implementation sequence of arguments [r1, r2...] is monotonically increasing.
                // 'index' tracks the index of the most recent error that was checked.
                while (true) {
                    if (index >= sorted.length) {
                        // all errors in the range were already checked -> no error in specified range
                        return false;
                    }
                    var error = sorted[index];
                    if (r.end <= error.start) {
                        // specified range ends before the error refered by 'index' - no error in range
                        return false;
                    }
                    if (ts.startEndOverlapsWithStartEnd(r.pos, r.end, error.start, error.start + error.length)) {
                        // specified range overlaps with error range
                        return true;
                    }
                    index++;
                }
            };
            function rangeHasNoErrors(r) {
                return false;
            }
        }
function prepareRangeContainsErrorFunction(errors, originalRange) {
            if (!errors.length) {
                return rangeHasNoErrors;
            }
            // pick only errors that fall in range
            var sorted = errors
                .filter(function (d) { return ts.rangeOverlapsWithStartEnd(originalRange, d.start, d.start + d.length); })
                .sort(function (e1, e2) { return e1.start - e2.start; });
            if (!sorted.length) {
                return rangeHasNoErrors;
            }
            var index = 0;
            return function (r) {
                // in current implementation sequence of arguments [r1, r2...] is monotonically increasing.
                // 'index' tracks the index of the most recent error that was checked.
                while (true) {
                    if (index >= sorted.length) {
                        // all errors in the range were already checked -> no error in specified range
                        return false;
                    }
                    var error = sorted[index];
                    if (r.end <= error.start) {
                        // specified range ends before the error refered by 'index' - no error in range
                        return false;
                    }
                    if (ts.startEndOverlapsWithStartEnd(r.pos, r.end, error.start, error.start + error.length)) {
                        // specified range overlaps with error range
                        return true;
                    }
                    index++;
                }
            };
            function rangeHasNoErrors(r) {
                return false;
            }
        }
formatting is not applied to ranges that contain parse errors.
This function will return a predicate that for a given text range will tell
if there are any parse errors that overlap with the range.