marks array. Enable Observable Plot under Libraries, wait until it is checked, then paste the whole editor.

Goal

Run every block and confirm the chart is visible.

document.body.innerHTML = '';
document.body.append(Plot.plot({ marks: [Plot.barY([{c:"Nairobi",u:21,s:2100},{c:"Mombasa",u:15,s:1500},{c:"Kisumu",u:15,s:1480},{c:"Nakuru",u:18,s:1750},{c:"Eldoret",u:12,s:1190}], { x: "c", y: "u" }), Plot.dot([{c:"Nairobi",u:21,s:2100},{c:"Mombasa",u:15,s:1500},{c:"Kisumu",u:15,s:1480},{c:"Nakuru",u:18,s:1750},{c:"Eldoret",u:12,s:1190}], { x: "c", y: "u" })] }));
console.log('many');

document.body.innerHTML = '';
document.body.append(Plot.plot({ marks: [Plot.barY([{c:"Nairobi",u:21,s:2100},{c:"Mombasa",u:15,s:1500},{c:"Kisumu",u:15,s:1480},{c:"Nakuru",u:18,s:1750},{c:"Eldoret",u:12,s:1190}], { x: "c", y: "u" })] }));
console.log('bar');

document.body.innerHTML = '';
document.body.append(Plot.plot({ marks: [Plot.lineY([{m:"Jan",mm:48,city:"Nairobi"},{m:"Feb",mm:55,city:"Nairobi"},{m:"Mar",mm:92,city:"Nairobi"},{m:"Apr",mm:150,city:"Nairobi"},{m:"Jan",mm:22,city:"Mombasa"},{m:"Apr",mm:80,city:"Mombasa"}], { x: "m", y: "mm", stroke: "city" })] }));
console.log('line');

console.log('many');