Robby the robot solution

KeyRock.js

function getCommands(field, power) {
    var sideLength = Math.sqrt(field.length);
    var starti = 0, startj = 0, endi = 0, endj = 0;
    for (let i = 0; i < sideLength; i++) {
        for (let j = 0; j < sideLength; j++) {
            if (field[i * sideLength + j] == 'S') {
                starti = i;
                startj = j;
            }
            if (field[i * sideLength + j] == 'T') {
                endi = i;
                endj = j;
            }
        }
    }
    var queue = [{i: starti, j: startj, d: 'n', p: power, path: [], visited: [[starti, startj].toString()]}];
    while (queue.length > 0) {
        let s = queue.shift();
        let i = s.i, j = s.j, d = s.d, p = s.p, path = s.path, visited = s.visited;
        if (i == endi && j == endj)
            return path.length <= power ? path : [];
        if (i < 0 || i >= sideLength || j < 0 || j >= sideLength || field[i * sideLength + j] == '#' || p == 0)
            continue;
        if (d == 'n') {
            let temp = path.slice();
            let v = visited.slice();
            if (j + 1 < sideLength && v.indexOf([i, j + 1].toString()) == -1) {
                temp.push('r');
                queue.push({i: i, j: j, d: 'e', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (j - 1 >= 0 && v.indexOf([i, j - 1].toString()) == -1) {
                temp.push('l');
                queue.push({i: i, j: j, d: 'w', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (v.indexOf([i - 1, j].toString()) == -1) {
                temp.push('f');
                v.push([i - 1, j].toString());
                queue.push({i: i - 1, j: j, d: 'n', p: p - 1, path: temp, visited: v});
            }
        }
        else if (d == 's') {
            let temp = path.slice();
            let v = visited.slice();
            if (j + 1 < sideLength && v.indexOf([i, j + 1].toString()) == -1) {
                temp.push('r');
                queue.push({i: i, j: j, d: 'w', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (j - 1 >= 0 && v.indexOf([i, j - 1].toString()) == -1) {
                temp.push('l');
                queue.push({i: i, j: j, d: 'e', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (v.indexOf([i + 1, j].toString()) == -1) {
                temp.push('f');
                v.push([i + 1, j].toString());
                queue.push({i: i + 1, j: j, d: 's', p: p - 1, path: temp, visited: v});
            }
        }
        else if (d == 'e') {
            let temp = path.slice();
            let v = visited.slice();
            if (i + 1 < sideLength && v.indexOf([i + 1, j].toString()) == -1) {
                temp.push('r');
                queue.push({i: i, j: j, d: 's', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (i - 1 >= 0 && v.indexOf([i - 1, j].toString()) == -1) {
                temp.push('l');
                queue.push({i: i, j: j, d: 'n', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (v.indexOf([i, j + 1].toString()) == -1) {
                temp.push('f');
                v.push([i, j + 1].toString());
                queue.push({i: i, j: j + 1, d: 'e', p: p - 1, path: temp, visited: v});
            }
        }
        else if (d == 'w') {
            let temp = path.slice();
            let v = visited.slice();
            if (i - 1 >= 0 && v.indexOf([i - 1, j].toString()) == -1) {
                temp.push('r');
                queue.push({i: i, j: j, d: 'n', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (i + 1 < sideLength && v.indexOf([i + 1, j].toString()) == -1) {
                temp.push('l');
                queue.push({i: i, j: j, d: 's', p: p - 1, path: temp, visited: v});
            }
            temp = path.slice();
            if (v.indexOf([i, j - 1].toString()) == -1) {
                temp.push('f');
                v.push([i, j - 1].toString());
                queue.push({i: i, j: j - 1, d: 'w', p: p - 1, path: temp, visited: v});
            }
        }
    }
    return [];
}