> is there a reason to use jsconsole/console.log over echo other than looks?
Yes, for cstrings in particular. Compare the outputs of the following examples
(all compiled with `-d:danger` to remove noise, and cleaned up slightly to make
it clearer):
Example 1: using echo with a regular Nim string
let str = "Hello world"
echo str
Run
The generated JS:
function toJSStr(s_33556901) {
// a big function to convert a nim string (array of numbers) to a
javascript string
// ...
}
function rawEcho() {
// a function that converts all of its arguments to js strings using
toJSStr, and then console.logs them
// ...
}
// the string "Hello world", represented as an array of numbers
var str_536870913 = [72,101,108,108,111,32,119,111,114,108,100];
rawEcho(str_536870913);
Run
Example 2: using echo with a cstring ("compatible string")
let str = cstring "Hello world"
echo str
Run
The generated JS:
function toJSStr(s_33556901) {
// a big function to convert a nim string (array of numbers) to a
javascript string
// ...
}
function rawEcho() {
// a function that converts all of its arguments to js strings using
toJSStr, and then console.logs them
// ...
}
function cstrToNimstr(c_33556898) {
// a large function that converts a JS string to an array of numbers (the
representation of a Nim string)
}
// the "Hello world" string as a JS string
var str_536870913 = "Hello world";
// echo by first converting the JS string to a Nim string
rawEcho(cstrToNimstr(str_536870913));
Run
Example3: using console.log with a cstring
import std/jsconsole
let str = cstring "Hello world"
console.log str
Run
The generated JS:
var str_536870914 = "Hello world";
console.log(str_536870914);
Run
As you can see the final output is the simplest with the lowest overhead. When
using the JS backend, a good rule of thumb is to use `string` when you want
compatibility with Nim libraries, and to use `cstring` when you want
compatibility with JS libraries, or smaller codegen output and faster execution.
