1 files changed, 48 insertions, 0 deletions
diff --git a/website/js/placeholder.js b/website/js/placeholder.js
new file mode 100644
index 0000000..748afe7
--- /dev/null
+++ b/website/js/placeholder.js
@@ -0,0 +1,48 @@
+(function() {
+  CodeMirror.defineOption("placeholder", "", function(cm, val, old) {
+    var prev = old && old != CodeMirror.Init;
+    if (val && !prev) {
+      cm.on("blur", onBlur);
+      cm.on("change", onChange);
+      onChange(cm);
+    } else if (!val && prev) {
+      cm.off("blur", onBlur);
+      cm.off("change", onChange);
+      clearPlaceholder(cm);
+      var wrapper = cm.getWrapperElement();
+      wrapper.className = wrapper.className.replace(" CodeMirror-empty", "");
+    }
+
+    if (val && !cm.hasFocus()) onBlur(cm);
+  });
+
+  function clearPlaceholder(cm) {
+    if (cm.state.placeholder) {
+      cm.state.placeholder.parentNode.removeChild(cm.state.placeholder);
+      cm.state.placeholder = null;
+    }
+  }
+  function setPlaceholder(cm) {
+    clearPlaceholder(cm);
+    var elt = cm.state.placeholder = document.createElement("pre");
+    elt.style.cssText = "height: 0; overflow: visible";
+    elt.className = "CodeMirror-placeholder";
+    elt.appendChild(document.createTextNode(cm.getOption("placeholder")));
+    cm.display.lineSpace.insertBefore(elt, cm.display.lineSpace.firstChild);
+  }
+
+  function onBlur(cm) {
+    if (isEmpty(cm)) setPlaceholder(cm);
+  }
+  function onChange(cm) {
+    var wrapper = cm.getWrapperElement(), empty = isEmpty(cm);
+    wrapper.className = wrapper.className.replace(" CodeMirror-empty", "") + (empty ? " CodeMirror-empty" : "");
+
+    if (empty) setPlaceholder(cm);
+    else clearPlaceholder(cm);
+  }
+
+  function isEmpty(cm) {
+    return (cm.lineCount() === 1) && (cm.getLine(0) === "");
+  }
+})();