I'm looking for a good JavaScript equivalent of the C/PHP printf() or for C#/Java programmers, String.Format() (IFormatProvider for .NET).
My basic requirement is a thousand separator format for numbers for now, but something that handles lots of combinations (including dates) would be good.
I realize Microsoft's Ajax library provides a version of String.Format(), but we don't want the entire overhead of that framework.
sprintf() function analog in JavaScript as Vue filter and String.prototype.format() extension:
/** * Returns a formatted string. * * @param template * @param values * @return string */ String.format = function (template, ...values) { let i = -1; function callback(exp, p0, p1, p2, p3, p4) { if (exp === '%%') return '%'; if (values[++i] === undefined) return undefined; exp = p2 ? parseInt(p2.substr(1)) : undefined; let base = p3 ? parseInt(p3.substr(1)) : undefined; let val; switch (p4) { case 's': val = values[i]; break; case 'c': val = values[i][0]; break; case 'f': val = parseFloat(values[i]).toFixed(exp); break; case 'p': val = parseFloat(values[i]).toPrecision(exp); break; case 'e': val = parseFloat(values[i]).toExponential(exp); break; case 'x': val = parseInt(values[i]).toString(base ? base : 16); break; case 'd': val = parseFloat(parseInt(values[i], base ? base : 10).toPrecision(exp)).toFixed(0); break; } val = typeof (val) == 'object' ? JSON.stringify(val) : val.toString(base); let sz = parseInt(p1); /* padding size */ let ch = p1 && p1[0] === '0' ? '0' : ' '; /* isnull? */ while (val.length < sz) val = p0 !== undefined ? val + ch : ch + val; /* isminus? */ return val; } let regex = /%(-)?(0?[0-9]+)?([.][0-9]+)?([#][0-9]+)?([scfpexd%])/g; return template.replace(regex, callback); } String.prototype.format = function() { return String.format(this, ...arguments); } const StringFormat = { install: (Vue, options) => { Vue.filter('format', function () { return String.format(...arguments); }); }, }; export default StringFormat; Original answer: JavaScript equivalent to printf/String.Format
If you need a printf, use printf
Looks like 90% of commenters never used printf with more complex format than just %d. I wonder how do they output, for example, money values?
(213.3244).toFixed(2) exists in JavaScript, other languages have other methods (C# has Decimal.Truncate(), or you use Math.Round()/Math.round()). Cultural information is also present in many languages. System.Globalization for C# is an example, (324).toLocaleString() in JavaScript. This answer also only works in Node.js, not the browser. Considering the question doesn't specify if its browser or node, this answer could be considered rather useless to the situation (tho helpful to others coming here). Template strings are the best solution here.
template string;String.padStartmight be the other thing ppl looking for. (See stackoverflow.com/questions/2686855/… )