Client-side JavaScript sprintf equivalent
I know I console.log
support at least some of the core functionality printf
from C via messing around, but I was curious how to use the implementation console.log
to create something similar to sprintf
, I know you can't just use .bind
or .apply
since it console.log
doesn't actually return line, so is there a way to get around this?
If this is actually not possible, is there some other little-known built-in implementation that is only a few lines of code from reaching sprintf
in JavaScript?
For those who don't know what exactly is sprintf
exactly, here is some documentation from the tutorial point . The usage example I'm looking for is below:
var string1 = sprintf("Hello, %s!", "world");
var string2 = sprintf("The answer to everything is %d.", 42);
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Keep it simple
var sprintf = (str, ...argv) => !argv.length ? str :
sprintf(str = str.replace(sprintf.token||"$", argv.shift()), ...argv);
Since Javascript handles data types automatically, there is no need for type parameters.
If you need to fill in, "15".padStart(5,"0")
= ("00000"+15).slice(-5)
= "00015"
.
Using
var sprintf = (str, ...argv) => !argv.length ? str :
sprintf(str = str.replace(sprintf.token||"$", argv.shift()), ...argv);
alert(sprintf("Success after $ clicks ($ seconds).", 15, 4.569));
sprintf.token = "_";
alert(sprintf("Failure after _ clicks (_ seconds).", 5, 1.569));
sprintf.token = "%";
var a = "%<br>%<br>%";
var b = sprintf("% plus % is %", 0, 1, 0 + 1);
var c = sprintf("Hello, %!", "world");
var d = sprintf("The answer to everything is %.", 42);
document.write(sprintf(a,b,c,d));
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Try to use , eval
.replace
var sprintf = function sprintf() {
// arguments
var args = Array.prototype.slice.call(arguments)
// parameters for string
, n = args.slice(1, -1)
// string
, text = args[0]
// check for `Number`
, _res = isNaN(parseInt(args[args.length - 1]))
? args[args.length - 1]
// alternatively, if string passed
// as last argument to `sprintf`,
// `eval(args[args.length - 1])`
: Number(args[args.length - 1])
// array of replacement values
, arr = n.concat(_res)
// `res`: `text`
, res = text;
// loop `arr` items
for (var i = 0; i < arr.length; i++) {
// replace formatted characters within `res` with `arr` at index `i`
res = res.replace(/%d|%s/, arr[i])
}
// return string `res`
return res
};
document.write(sprintf("%d plus %d is %d", 0, 1, 0 + 1)
+ "<br>"
+ sprintf("Hello, %s!", "world")
+ "<br>"
+ sprintf("The answer to everything is %d.", 42)
);
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