solution.js

/**
 * @param {number[]} rec1
 * @param {number[]} rec2
 * @return {boolean}
 */
var isRectangleOverlap = function(rec1, rec2) {
    if (rec1[0] >= rec2[2] || rec2[0] >= rec1[2]) {
        return false
    } else if (rec1[1] >= rec2[3] || rec2[1] >= rec1[3]) {
        return false
    }
    
    return true
};