javascript - Console is displaying code content instead of executing it -

i modify function collecting array difference here handle multi-dimensional array, code not working expected , debugging has been problematic because console.log displaying content of code instead of executing it...

function arrdiff(xs, yx, d) {    const apply = f => x => f(x);    const flip = f => y => x => f(x)(y);    const concat = y => xs => xs.concat(y);    const createmap = xs => new map(xs);    const filter = f => xs => xs.filter(apply(f));      //left difference    const differencel = xs => yx => {      const zs = createmap(yx);      return filter(([k, x]) => zs.has(x) ? false : true)(xs);    };    if (d == 'left') return differencel    //right difference    const difference2 = flip(differencel);    if (d == 'join') return difference2;      //union    if (d == "union") {      const map = new map([...xs, ...yx]);      return map;    }    // symmetric difference    const difference = yx => xs => concat(differencel(xs)(yx))      (flip(differencel)(xs)(yx));    return difference;  }  const xs = [    ['a', 1],    ['b', 2],    ['c', 2],    ['d', 3],    ['e', 4],    ['f', 5]  ];  const ys = [    ['g', 0],    ['h', 1],    ['f', 2],    ['b', 3],    ['c', 3],    ['a', 3],    ['e', 6],    ['h', 7]  ];  console.log(arrdiff(xs, ys, 'left'));