➕add/concate (+)
number addition / string concatenation.
1 + 2 // number addition
'the' + 'fox' // string concatenation
// result conversion
// -------------------------------------------------------------
1 + 2, // 3
'1' + 2, // '12' (2 -> '2')
'1' + '2', // '12'
1 + {}, // '1[object Object]' ({} -> object to primitive)
true + true, // 2 (true -> 1)
2 + null, // 2 (null -> 0)
3 + undefined, // NaN (undefined -> NaN)
// ❗ `+` mixed with strings and numbers is not associative
// -------------------------------------------------------------
(1 + 2) + ' cats', // '3 cats' (addition -> concatenation)
1 + (2 + ' cats'), // '12 cats' (2 concatenations)Last updated