echarts prompt box plus pictures

Use tooltip's formatter method and es6's string template

`<img src="${require('@/assets/img/u123.png')}">`

This will dynamically import pictures

tooltip:{
    
    
 formatter: function (params) {
    
    
	 var Val = params.marker + params.data.source + `<img src="${require('@/assets/img/u123.png')}">` + params.value
	 return Val;
 },
},