97.27% fast javascript very easy to understand solution
Visit my youtube! Thank you!\nhttps://www.youtube.com/channel/UCkhEaNAOO8tig5NHqqxXIeg\n\n/**\n * Definition for a binary tree node.\n * function TreeNode(val, 
Visit my youtube! Thank you!\nhttps://www.youtube.com/channel/UCkhEaNAOO8tig5NHqqxXIeg\n```\n/**\n * Definition for a binary tree node.\n * function TreeNode(val, left, right) {\n *     this.val = (val===undefined ? 0 : val)\n *     this.left = (left===undefined ? null : left)\n *     this.right = (right===undefined ? null : right)\n * }\n */\n/**\n * @param {TreeNode} root\n * @param {number} low\n * @param {number} high\n * @return {number}\n */\nvar rangeSumBST = function(root, low, high) {\n    let sum = 0;\n\n    let iterate = (node=root) =>{\n        if(!node) return;\n\n        iterate(node.left)\n\n        if(node.val>=low && node.val<=high) sum += node.val;\n\n        iterate(node.right)\n    }\n\n    iterate()\n    return sum;\n};\n```
['JavaScript']