null undefined wrong type numbers: 0, negative, decimals strings: case, whitespace, special characters, digits, punctuation, new lines arrays: sort order asc/desc arrays, strings, & objects: empty, out of bounds/key doesn’t exist
null undefined wrong type numbers: 0, negative, decimals strings: case, whitespace, special characters, digits, punctuation, new lines arrays: sort order asc/desc arrays, strings, & objects: empty, out of bounds/key doesn’t exist