’dom‘ is undefined

[muyangcaiwei]

When the component(written with echarts) is first loaded，the component is blank , it told me that the 'dom' is undefined,
when i click somewhere else in the component, the 'dom' has value and component is normally displayed.
Is there something wrong ？

[muyangcaiwei]

the code is : var chart = this.$echarts.init(this.$refs.canvas)
it seems like this.$refs.canvas is undefined in the first time