Cache Child Props

Cache the child props to prevent React from re-rendering unnessesarily.
The biggest culprits were the default accessors.  The defaults for each
attribute are now computed once, and re-used when required.

Author: Chris Thomas

.eslintrc

@@ -19,8 +19,8 @@
     "**/dist/",
     "**/es/"
   ],
-  "settings":{
-    "react":{
+  "settings": {
+    "react": {
       "version": "detect"
     }
   },
@@ -31,12 +31,14 @@
   },
   "rules": {
     "consistent-return": 0,
-    "max-len": [1, 110, 4],
-    "max-params": ["error", 6],
+    "max-params": [
+      "error",
+      6
+    ],
     "object-curly-spacing": 0,
     "babel/object-curly-spacing": 2,
-    "jest/require-top-level-describe":"error",
+    "jest/require-top-level-describe": "error",
     "react/prop-types": "off",
     "prettier/prettier": "warn"
   }
-}
+}

packages/react-vis/src/plot/xy-plot.js

@@ -188,6 +188,22 @@ class XYPlot extends React.Component {
     }
   };
 
+  _childPropCache = Object.create(null);
+
+  /**
+   * Memoizes the props of the child.
+   * This is keyed off of the childs 'key' property or defaults to its index.
+   * @param {number} index The index of the child
+   * @param {object} newValues The childs props
+   */
+  _getChildProps(index, newValues) {
+    const key = newValues.key || `@@series-${index}`;
+    const cached = this._childPropCache[key];
+    if (!equal(cached, newValues)) {
+      this._childPropCache[key] = {...newValues};
+    }
+    return this._childPropCache[key];
+  }
   /**
    * Prepare the child components (including series) for rendering.
    * @returns {Array} Array of child components.
@@ -201,6 +217,7 @@ class XYPlot extends React.Component {
     const children = React.Children.toArray(this.props.children);
     const seriesProps = getSeriesPropsFromChildren(children);
     const XYPlotValues = getXYPlotValues(props, children);
+
     return children.map((child, index) => {
       let dataProps = null;
       if (seriesProps[index]) {
@@ -209,21 +226,26 @@ class XYPlot extends React.Component {
         const {seriesIndex} = seriesProps[index];
         dataProps = {data: data[seriesIndex]};
       }
-      return React.cloneElement(child, {
+
+      const childProps = this._getChildProps(index, {
         ...dimensions,
         animation,
-        ...(dataProps && child.type.prototype && child.type.prototype.render
-          ? {
-              ref: ref =>
-                (this[`series${seriesProps[index].seriesIndex}`] = ref)
-            }
-          : {}),
         ...seriesProps[index],
         ...scaleMixins,
         ...child.props,
         ...XYPlotValues[index],
         ...dataProps
       });
+
+      const refProp =
+        dataProps && child.type.prototype && child.type.prototype.render
+          ? {
+              ref: ref =>
+                (this[`series${seriesProps[index].seriesIndex}`] = ref)
+            }
+          : {};
+
+      return React.cloneElement(child, {...childProps, ...refProp});
     });
   }
   /**

packages/react-vis/src/utils/scales-utils.js

@@ -763,6 +763,24 @@ export function extractScalePropsFromProps(props, attributes) {
   return result;
 }
 
+const ALL_ATTRIBUTES = [
+  'x',
+  'y',
+  'radius',
+  'angle',
+  'color',
+  'fill',
+  'stroke',
+  'opacity',
+  'size'
+];
+
+const defaultScaleProps = ALL_ATTRIBUTES.reduce((result, attr) => {
+  result[`get${toTitleCase(attr)}`] = d => d[attr];
+  result[`get${toTitleCase(attr)}0`] = d => d[`${attr}0`];
+  return result;
+}, {});
+
 /**
  * Extract the missing scale props from the given data and return them as
  * an object.
@@ -776,17 +794,21 @@ export function getMissingScaleProps(props, data, attributes) {
   const result = {};
   // Make sure that the domain is set pad it if specified
   attributes.forEach(attr => {
-    if (!props[`get${toTitleCase(attr)}`]) {
-      result[`get${toTitleCase(attr)}`] = d => d[attr];
+    const titleCaseAttr = toTitleCase(attr);
+    const getKey = `get${titleCaseAttr}`;
+    const get0Key = `get${titleCaseAttr}0`;
+
+    if (!props[getKey]) {
+      result[getKey] = defaultScaleProps[getKey];
     }
-    if (!props[`get${toTitleCase(attr)}0`]) {
-      result[`get${toTitleCase(attr)}0`] = d => d[`${attr}0`];
+    if (!props[get0Key]) {
+      result[get0Key] = defaultScaleProps[get0Key];
     }
     if (!props[`${attr}Domain`]) {
       result[`${attr}Domain`] = getDomainByAccessor(
         data,
-        props[`get${toTitleCase(attr)}`] || result[`get${toTitleCase(attr)}`],
-        props[`get${toTitleCase(attr)}0`] || result[`get${toTitleCase(attr)}0`],
+        props[getKey] || result[getKey],
+        props[get0Key] || result[get0Key],
         props[`${attr}Type`]
       );
       if (props[`${attr}Padding`]) {