JavaScript

JavaScript is a high-level programming language that runs in every major web browser and makes web pages interactive. Brendan Eich created it at Netscape in 1995, and it is standardised by Ecma International under the name ECMAScript. Runtimes such as Node.js, released in 2009, also let it run on servers, so many fintech dashboards and APIs are written in it from end to end. In crypto, JavaScript and its typed variant TypeScript power most dApp front ends: libraries such as ethers.js and web3.js let a web page read blockchain data and ask a browser wallet such as MetaMask to sign transactions, while the on-chain logic itself is usually written in a language such as Solidity. Despite the name, it is a separate language from Java.