Cursor Movements

cursor.ts

function moveCursorTo(node: Node, offset: number, native: Selection) {
    // COMPAT: IE 11 does not support Selection.setBaseAndExtent, fallback to collapse
    if (native.setBaseAndExtent) {
        native.setBaseAndExtent(node, offset, node, offset);
    } else {
        native.collapse(node, offset);
    }
}

function selectFrom(start: Node, startOffset: number, end: Node, endOffset: number, native: Selection) {
    // COMPAT: IE 11 does not support Selection.setBaseAndExtent
    if (native.setBaseAndExtent) {
        // COMPAT: Since the DOM range has no concept of backwards/forwards
        // we need to check and do the right thing here.
        // tslint:disable-next-line:no-bitwise
        let isBackward = end.compareDocumentPosition(start) & Node.DOCUMENT_POSITION_PRECEDING;
        if (isBackward) {
            native.setBaseAndExtent(end, endOffset, start, startOffset);
        } else {
            native.setBaseAndExtent(start, startOffset, end, endOffset);
        }
    } else {
        // COMPAT: IE 11 does not support Selection.setBaseAndExtent, fallback to addRange
        native.removeAllRanges();
        let range = document.createRange();
        range.setStart(start, startOffset);
        range.setEnd(end, endOffset);
        native.addRange(range);
    }
}