What should I do if echarts referenced by uniapp is not displayed?

If you are using uniapp to develop an application and want to reference echarts for data visualization display, but find that no matter how hard you try, the echarts chart cannot be displayed normally, then you may need to perform the following debugging steps:

1. Confirm whether echarts is imported correctly

Before using echarts, you need to import the js file of echarts first. You can add the following code to index.html to try to introduce it:

<script src="//cdn.bootcss.com/echarts/4.1.0/echarts.min.js"></script>

If your project does not use CDN, you need to download the js file of echarts and introduce it into the project. Make sure the path to the echarts.js file is correct, and also confirm whether echarts.js exports the echarts object.

2. Confirm whether the container is set up

In uniapp, you can use the provided components to create a container to place echarts. Before using echarts, you need to define a container.

The following is an example:

<template>
  <view class="echarts">
    <ec-canvas id="canvas-dom"></ec-canvas>
  </view>
</template>

Among them, <ec-canvas> is a built-in component of uniapp for placing charts. You need to specify an id within the component, which will be used for subsequent initialization operations.

3. Initialize echarts

After creating the container, you need to initialize echarts in the js code. Data and configuration items need to be specified in the initialization code, and the chart is rendered in the container defined previously.

The following is an example:

import * as echarts from 'echarts';

export default {
  onLoad() {
    this.initChart();
  },
  methods: {
    initChart() {
      this.$nextTick(() => {
        const ec = this.$refs['chart-dom'].ref;
        const chart = echarts.init(ec, null, {
            width: this.getDomWidth('chart'),
            height: this.getDomHeight('chart')
        });
        let option = {
          title: {
            text: '统计图表'
          },
          ... // 其他配置项
        };
        chart.setOption(option);
      });
    }
  }
}

In this example, the $nextTick function of uniapp is used to ensure that the initialization of echarts will be executed after the chart-dom element is rendered and the chart- The method of dom element is this.$refs['chart-dom'].ref. You can also use other methods to obtain DOM elements for initialization.

4. Confirm whether the data is correct

If there are no problems with the previous steps, but the echarts chart still cannot be displayed normally, then it is very likely that there is a problem with the data. It is necessary to confirm whether the data is correct and whether the specific rendered data matches.

To sum up, if you encounter the problem that the echarts referenced in uniapp are not displayed, you can first focus on the above points to troubleshoot.

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