1 files changed, 47 insertions, 0 deletions
diff --git a/app/assets/javascripts/behaviors/bind_in_out.js b/app/assets/javascripts/behaviors/bind_in_out.js
new file mode 100644
index 00000000000..886f127b06b
--- /dev/null
+++ b/app/assets/javascripts/behaviors/bind_in_out.js
@@ -0,0 +1,47 @@
+class BindInOut {
+  constructor(bindIn, bindOut) {
+    this.in = bindIn;
+    this.out = bindOut;
+
+    this.eventWrapper = {};
+    this.eventType = /(INPUT|TEXTAREA)/.test(bindIn.tagName) ? 'keyup' : 'change';
+  }
+
+  addEvents() {
+    this.eventWrapper.updateOut = this.updateOut.bind(this);
+
+    this.in.addEventListener(this.eventType, this.eventWrapper.updateOut);
+
+    return this;
+  }
+
+  updateOut() {
+    this.out.textContent = this.in.value;
+
+    return this;
+  }
+
+  removeEvents() {
+    this.in.removeEventListener(this.eventType, this.eventWrapper.updateOut);
+
+    return this;
+  }
+
+  static initAll() {
+    const ins = document.querySelectorAll('*[data-bind-in]');
+
+    return [].map.call(ins, anIn => BindInOut.init(anIn));
+  }
+
+  static init(anIn, anOut) {
+    const out = anOut || document.querySelector(`*[data-bind-out="${anIn.dataset.bindIn}"]`);
+
+    if (!out) return null;
+
+    const bindInOut = new BindInOut(anIn, out);
+
+    return bindInOut.addEvents().updateOut();
+  }
+}
+
+export default BindInOut;