Frappe chart in page ERPNEXT v8

I created a page to display graphics,
I tried a basic js script but it gives an error in the console “frappe.chart is not a constructor”
Someone can take a look and point out the error in this.
Erpnext V8 version
Frappe V8 version

Code JS:

frappe.pages[‘prueba’].on_page_load = function(wrapper) {
var page = frappe.ui.make_app_page({
parent: wrapper,
title: ‘KPI gestion oportunidades’,
single_column: true

wrapper = $(wrapper).find('.layout-main-section');
		<div id="chart"></div>

const chart_data = {
	labels: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
	datasets: [

const graph = new frappe.chart({
	parent: "#chart",
	data: chart_data,
	type: 'line'

setTimeout(function () {graph.refresh()}, 1);


Code HTML:

<div id="chart"