Function setScrollLeft

static/editor.md/lib/codemirror/lib/codemirror.js:3796–3803

(cm, val, isScroller)

  // Sync scroller and scrollbar, ensure the gutter elements are
  // aligned.
  function setScrollLeft(cm, val, isScroller) {
    if (isScroller ? val == cm.doc.scrollLeft : Math.abs(cm.doc.scrollLeft - val) < 2) return;
    val = Math.min(val, cm.display.scroller.scrollWidth - cm.display.scroller.clientWidth);
    cm.doc.scrollLeft = val;
    alignHorizontally(cm);
    if (cm.display.scroller.scrollLeft != val) cm.display.scroller.scrollLeft = val;
    cm.display.scrollbars.setScrollLeft(val);
  }

  // Since the delta values reported on mouse wheel events are
  // unstandardized between browsers and even browser versions, and