No ‘Access-Control-Allow-Origin’ header is present on the requested resource—when trying to get data from a REST API

This answer covers a lot of ground, so it’s divided into three parts: How to use a CORS proxy to get around “No Access-Control-Allow-Origin header” problems How to avoid the CORS preflight How to fix “Access-Control-Allow-Origin header must not be the wildcard” problems How to use a CORS proxy to avoid “No Access-Control-Allow-Origin header” problems … Read more

Parse JSON in JavaScript? [duplicate]

The standard way to parse JSON in JavaScript is JSON.parse() The JSON API was introduced with ES5 (2011) and has since been implemented in >99% of browsers by market share, and Node.js. Its usage is simple: Expand snippet The only time you won’t be able to use JSON.parse() is if you are programming for an … Read more

What is the JavaScript version of sleep()?

2017 — 2021 update Since 2009 when this question was asked, JavaScript has evolved significantly. All other answers are now obsolete or overly complicated. Here is the current best practice:  Run code snippet This is it. await sleep(<duration>). Or as a one-liner: Note that, await can only be executed in functions prefixed with the async keyword, or at the … Read more

How to format a JavaScript date

For custom-delimited date formats, you have to pull out the date (or time) components from a DateTimeFormat object (which is part of the ECMAScript Internationalization API), and then manually create a string with the delimiters you want. To do this, you can use DateTimeFormat#formatToParts. You could destructure the array, but that is not ideal, as the array output depends … Read more

How to append something to an array?

Use the Array.prototype.push method to append values to the end of an array:  Run code snippet You can use the push() function to append more than one value to an array in a single call:  Run code snippet Update If you want to add the items of one array to another array, you can use firstArray.concat(secondArray):  Run code snippet Update … Read more

tech