Aiming for the String.Format of C #, which is very easy to use, I have searched for something similar to be used in my JavaScript codes.
I found some implementations that are somewhat problematic, so I would like you to have someone who has a succinct and functional code that shares it with our community.
Something that works this way:
String.Format("String {0}.", "format");
//Resultado: "String format"
I found some implementations in the OS. I do not know if any of you get what you want.
One of them is sprintf.js , it seems to be one of the most complete implementations.
Other :
if (!String.prototype.format) {
String.prototype.format = function() {
var args = arguments;
return this.replace(/{(\d+)}/g, function(match, number) {
return typeof args[number] != 'undefined'
? args[number]
: match
;
});
};
}
Usage:
"{0} is dead, but {1} is alive! {0} {2}".format("ASP", "ASP.NET")
I use replace.
var teste = "Teste {0}";
teste = teste.replace("{0}", "Sucesso");
I use this implementation:
if (!String.prototype.format)
{
String.prototype.format = function()
{
var args = arguments;
if (typeof args[0] != "object")
{
return this.replace(/{\d+}/g, function(m)
{
var index = Number(m.replace(/\D/g, ""));
return (args[index] ? args[index] : m);
});
}
else
{
var obj = args[0],
keys = Object.keys(obj);
return this.replace(/{\w+}/g, function(m)
{
var key = m.replace(/{|}/g, "");
return (obj.hasOwnProperty(key) ? obj[key] : m);
});
}
};
}
Uses:
"Test {0} Test {1} Test {2} Test {0}".format("str1", "str2")
Test str1 Test str2 Test {2} Test str1 - index 2 not defined
"Test {nome} Test {idade} Test {birth}".format({nome: "str1", idade: 15})
Test str1 Test 15 Test {birth} - 'birth' was not defined
I know you do not answer your question exactly, but when I need to interpolate variables with javascript text, I use the following method:
var nome = 'João da Silva', idade = 22, nacionalidade = 'Brasileiro';
var string = [
'Nome: ', nome, '\n'
'Idade: ', idade, '\n'
'Nacionalidade: ', nacionalidade].join("");
This code returns:
Nome: João da Silva Idade: 22 Nacionalidade: Brasileiro
I personally think this code is more readable than the code below:
var string = 'Nome: ' + nome + '\n' +
'Idade: ' + idade + '\n' +
'Nacionalidade: ' + nacionalidade;
Furthermore, the difference in performance of using join or + is not something that will impact your page.
I use this method in my project:
function format (fmtstr) {
var args = Array.prototype.slice.call(arguments, 1);
return fmtstr.replace(/\{(\d+)\}/g, function (match, index) {
return args[index];
});
}