ECharts Label Formatter

This tool encapsulates the domain logic for ECharts label formatter. It accepts inputs describing chart type, label scope, and a formatter expression. It validates syntax and expands placeholders into sample outputs using a provided data set. The goal is to produce predictable label strings for review before integrating into charts.
Conceptually, the tool treats placeholders such as {value}, {name}, {seriesName}, and {percent} as tokens. It substitutes tokens with sample data and applies locale aware number formatting when requested. It supports simple string templates and basic validation to catch obvious errors like unknown placeholders or missing values.
Beneficiaries include data visualization developers, BI engineers, and analysts who design dashboards with ECharts. Unique value lies in testable preview of label outputs, consistency across charts, and quick iteration. Core features include grouped inputs, placeholder support, sample data, locale options, and export of formatter templates for reuse.
Use cases include axis label formatting for bar charts, pie chart percentage labels, and tooltip lines that summarize values. The tool is not a general code generator; it does not emit a complete chart configuration code but focuses on validating and illustrating how a given formatter will render under typical data.