Number Methods: JavaScript Quick Bits
We rarely need to access prototype methods on primitive types like plain numbers and strings, but we can...even when it seems like we can't. // Primitive access 'word'.split(''); // [ 'w', 'o', 'r', 'd' ] // What about numbers? 200.toString(); // SyntaxError: Identifier directly after number. That doesn't seem to work. This is because all regular numbers are decimals in JavaScript (double-precision floats, to be specific), so the period as part of the number has priority over the dot period as dot notation. 1; // 1 1.; // 1 1.0; // 1 [ 1, 1., 1.0 ].every(value => value === 1); // true As far as the JavaScript engine is concerned, these are the same code: 200.toString(); // SyntaxError: Identifier directly after number. 200toString(); // SyntaxError: Identifier directly after number. So how do we access prototype methods? With a second period. 200..toString(); // '200' 200..toFixed(2); // '200.00' The first period is part of the number; the second period is for dot notation property access. If two periods seems wrong, you can use bracket notation instead. 200['toFixed'](2); // '200.00' But you'll miss out on silly code like this: [...3..toFixed(2)][1]; // '.' Hope you enjoyed!
We rarely need to access prototype methods on primitive types like plain numbers and strings, but we can...even when it seems like we can't.
// Primitive access
'word'.split(''); // [ 'w', 'o', 'r', 'd' ]
// What about numbers?
200.toString(); // SyntaxError: Identifier directly after number.
That doesn't seem to work. This is because all regular numbers are decimals in JavaScript (double-precision floats, to be specific), so the period as part of the number has priority over the dot period as dot notation.
1; // 1
1.; // 1
1.0; // 1
[ 1, 1., 1.0 ].every(value => value === 1); // true
As far as the JavaScript engine is concerned, these are the same code:
200.toString(); // SyntaxError: Identifier directly after number.
200toString(); // SyntaxError: Identifier directly after number.
So how do we access prototype methods? With a second period.
200..toString(); // '200'
200..toFixed(2); // '200.00'
The first period is part of the number; the second period is for dot notation property access.
If two periods seems wrong, you can use bracket notation instead.
200['toFixed'](2); // '200.00'
But you'll miss out on silly code like this:
[...3..toFixed(2)][1]; // '.'
Hope you enjoyed!
