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Rooted by: Check Even Number
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  • Code 
    const isEven = n => {
  if (n != parseInt(n)) return undefined;
  return n % 2 ? false : true;
};
     Preloaded Code 
                                                                                                                                                              _=n=>!(n%1)
    Test Cases 
    const expect = require("chai").expect;
describe("Solution", function() {
  it("should be true for 4", function() {
    expect(isEven(4)).to.equal(true);
  });
  it("should be false for 1", function() {
    expect(isEven(1)).to.equal(false);
  });
  it("should be undefined for 1.5", function() {
    expect(isEven(1.5)).to.equal(undefined);
  });
  it("should be undefined for NaN", function() {
    expect(isEven(NaN)).to.equal(undefined);
  });
  it("should be undefined for Infinity", function() {
    expect(isEven(Infinity)).to.equal(undefined);
  });
  it("should be undefined for -Infinity", function() {
    expect(isEven(NaN)).to.equal(undefined);
  });
  it("should be undefined for undefined", function() {
    expect(isEven(undefined)).to.equal(undefined);
  });
});
    View Run Output
  • Code
    • isEven = number => number %2 === 0 ?
    • true: number %1 === 0 ?
    • false : undefined;
    • const isEven = n => {
    • if (n != parseInt(n)) return undefined;
    • return n % 2 ? false : true;
    • };