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I am trying to define a callback function in my chartJS options. for some reason, i get this error on my label definition:

Type '(tooltipItem: ChartTooltipItem, data: ChartData) => number | number[] | ChartPoint' is not assignable to type '(tooltipItem: ChartTooltipItem, data: ChartData) => string | string[]'. What am I doing wrong?

options: {
    tooltips: {
        callbacks: {
          title: (tooltipItems, data) => {
            return '';
          },
            label: (tooltipItem, data) => {
            const datasetLabel = '';
            return data.datasets[tooltipItem.datasetIndex].data[tooltipItem.index];
          }
        }
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    Hi, Well it's basically what the error is telling you, your returning string & string[ ] when number types expected, if you provide a stackblitz or add details on your example that repeats your error I gladley fork or give example code. Else i recommend reading this and this SO posts. Commented Nov 28, 2020 at 21:02
  • It may be too large for a stackblitz but its compiling fine but it justs has that red underline error. it looks like it's coming from the library node_modules/@types/chart.js/index.d.ts:242:9 242 label?(tooltipItem: ChartTooltipItem, data: ChartData): string | string[]; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The expected type comes from property 'label' which is declared here on type 'ChartTooltipCallback' Commented Nov 30, 2020 at 16:41
  • Not sure what you mean to big, you only need to replicate the issue itself. It's from the typings folder for the library Commented Nov 30, 2020 at 20:31
  • Its weird but I got it working by just adding the any type to the parameters like this: label: (tooltipItem, data: any) Commented Nov 30, 2020 at 21:21
  • 1
    the correct way would be so figure out your typing issues if it's the typings/lib thats the problem itself if so using "any" is one way to go :) Commented Nov 30, 2020 at 21:41
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