JSFiddle - React, Tailwind, and code Playground
JavaScript
var str = '[[1, 2, 3], [4, 5, 6], [7, 8, 9]]';
var arr = JSON.parse("[" + str + "]");
console.log(arr[0][0]); // [1, 2, 3]
console.log(arr[0][0][0]); // 1
var str = '[[1, 2, 3], [4, 5, 6], [7, 8, 9]]';
var arr = JSON.parse("[" + str + "]");
console.log(arr[0][0]); // [1, 2, 3]
console.log(arr[0][0][0]); // 1