fix(stock): avoid mutating stock data item (#3349)

Author: floydspace

__tests__/unit/plots/stock/data-spec.ts

@@ -3,7 +3,7 @@ import { TREND_FIELD, TREND_UP, TREND_DOWN, Y_FIELD } from '../../../../src/plot
 
 describe('stock data', () => {
   it('stock data', () => {
-    const yField = ['start', 'end', 'max', 'min'];
+    const yField: [string, string, string, string] = ['start', 'end', 'max', 'min'];
     const originalData = [
       { date: '2015-11-19', start: 8.18, max: 8.33, min: 7.98, end: 8.32, volumn: 1810, money: 14723.56 },
       { date: '2015-11-18', start: 8.37, max: 8.6, min: 8.03, end: 8.09, volumn: 2790.37, money: 23309.19 },
@@ -49,7 +49,7 @@ describe('stock data', () => {
   });
 
   it('start = end', () => {
-    const yField = ['start', 'end', 'max', 'min'];
+    const yField: [string, string, string, string] = ['start', 'end', 'max', 'min'];
     const originalData = [
       { date: '2015-11-19', start: 8.18, max: 8.33, min: 7.98, end: 8.18, volumn: 1810, money: 14723.56 },
     ];
@@ -70,7 +70,7 @@ describe('stock data', () => {
   });
 
   it('contain invalid value', () => {
-    const yField = ['start', 'end', 'max', 'min'];
+    const yField: [string, string, string, string] = ['start', 'end', 'max', 'min'];
     const originalData = [
       { date: '2015-11-19', start: undefined, max: 8.33, min: 7.98, end: null, volumn: 1810, money: 14723.56 },
     ];
@@ -89,4 +89,33 @@ describe('stock data', () => {
       },
     ]);
   });
+
+  it('does not mutate original data item', () => {
+    const yField: [string, string, string, string] = ['start', 'end', 'max', 'min'];
+    const originalData = [
+      { date: '2015-11-19', start: 8.18, max: 8.33, min: 7.98, end: 8.18, volumn: 1810, money: 14723.56 },
+    ];
+    const data = getStockData(originalData, yField);
+    expect(data[0]).not.toBe(originalData[0]);
+    expect(data).toEqual([
+      {
+        date: '2015-11-19',
+        start: 8.18,
+        max: 8.33,
+        min: 7.98,
+        end: 8.18,
+        volumn: 1810,
+        money: 14723.56,
+        [TREND_FIELD]: TREND_UP,
+        [Y_FIELD]: [8.18, 8.18, 8.33, 7.98],
+      },
+    ]);
+  });
+
+  it('contain invalid data item', () => {
+    const yField: [string, string, string, string] = ['start', 'end', 'max', 'min'];
+    const originalData = [null] as unknown as Record<string, any>[];
+    const data = getStockData(originalData, yField);
+    expect(data).toEqual([null]);
+  });
 });

src/plots/stock/utils.ts

@@ -6,9 +6,10 @@ import { TREND_FIELD, TREND_DOWN, TREND_UP, Y_FIELD } from './constant';
  * @param data
  * @param yField
  */
-export function getStockData(data, yField) {
-  return map(data, (obj) => {
-    if (isArray(yField)) {
+export function getStockData(data: Record<string, any>[], yField: [string, string, string, string]) {
+  return map(data, (item) => {
+    const obj = item && { ...item };
+    if (isArray(yField) && obj) {
       const [open, close, high, low] = yField;
       obj[TREND_FIELD] = obj[open] <= obj[close] ? TREND_UP : TREND_DOWN;
       obj[Y_FIELD] = [obj[open], obj[close], obj[high], obj[low]];