Function updateLineBackground

external/.scrollLibs.js:3332–3349

(cm, lineView)

  }

  function updateLineBackground(cm, lineView) {
    var cls = lineView.bgClass ? lineView.bgClass + " " + (lineView.line.bgClass || "") : lineView.line.bgClass
    if (cls) {
      cls += " CodeMirror-linebackground"
    }
    if (lineView.background) {
      if (cls) {
        lineView.background.className = cls
      } else {
        lineView.background.parentNode.removeChild(lineView.background)
        lineView.background = null
      }
    } else if (cls) {
      var wrap = ensureLineWrapped(lineView)
      lineView.background = wrap.insertBefore(elt("div", null, cls), wrap.firstChild)
      cm.display.input.setUneditable(lineView.background)
    }
  }

  // Wrapper around buildLineContent which will reuse the structure
  // in display.externalMeasured when possible.