JavaScript Error3 Fixes Available

TypeError: Cannot read properties of undefined (reading 'bgColor')

TypeError: Cannot read properties of undefined (reading 'bgColor')

What does this error mean?

This error commonly occurs in dashboard or charting libraries (like Chart.js, Recharts, or custom UI kits) when trying to access style properties like 'bgColor' or 'backgroundColor' on an object that doesn't exist. It usually means an item in your data array is null/undefined, or the configuration object structure doesn't match what the library expects.

Common Causes

A data point in your chart dataset is missing or undefined
The configured theme object hasn't loaded before the component renders
A loop is iterating over an array that has 'gaps' (sparse array)
Accessing styles.bgColor on an element that failed to match a selector

How to Fix It (3 Solutions)

Filter out undefined data points

Remove any null or undefined values from your dataset before passing it to the chart.

Code

// ❌ Crashes if any item is undefined
const colors = data.map(item => item.style.bgColor);

// ✅ Safe: Filter first
const validData = data.filter(item => item && item.style);
const colors = validData.map(item => item.style.bgColor);

Use Optional Chaining with Default

Safely access the property and provide a fallback color (like transparent or grey).

Code

// returns undefined instead of throwing
const color = item?.style?.bgColor; 

// returns '#f00' if bgColor is missing
const color = item?.style?.bgColor ?? '#f00';

Validate your data structure

Use our JSON Formatter to inspect your raw data and find the missing objects.

Fix this error faster with our free tool

JSON Formatter (Debug Data)

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