How to retrieve custom list items in SharePoint online

Question

I wan to know that how to retrieve custom list items and display them in content editor web part in sharepoint online classic experience. For example i have a list name ( companyinfo ) having two columns 'Company & Industry' and i have added content editor web part to page and link it to external HTML file which conatin an submit button. So when i click that button i wan to display list item. Now i want JavaScript/ Resftful API code to get items into that web part.