javascript - Jasmine test not passing when function returning correct result -

have simple function returning value:

obj.id = function(id) {     if (!id) {         throw new error('obj.id: no param');     } else if (typeof(id) === 'string') {         return obj.doc.getelementbyid(id);     } else {         return null;     } }; 

running test:

it('should return null if passed parameter not string', function() {     expect(function() {         obj.id({});     }).tobenull(); }); 

test fails pass though should pass.

it('should throw error if no parameter passed in', function() {     expect(function() {         obj.id();     }).tothrow(new error('obj.id: no param')); }); 

this 1 passes.

any ideas?

you're passing {} variable id function. though object has no keys, empty object evaluates true when used in if condition

you can prove using this:

({}) ? console.log('not falsey') : console.log('falsey'); // -> outputs 'not falsey' 

maybe can use hasownproperty() function instead?

({}.hasownproperty()) ? console.log('not empty') : console.log('empty'); // -> outputs 'empty'