I have following snippet of javascript code:
var someValue = 100;
var anotherValue = 555;
alert('someValue is {0} and anotherValue is {1}'.format(someValue, anotherValue));
getting following error:
Uncaught TypeError: undefined is not a function
what am i missing, here ?
String.format is not a native String extension. It's pretty easy to extend it yourself:
if (!String.prototype.format) {
String.prototype.format = function(...args) {
return this.replace(/({d+})/g, function(a) {
return args[+(a.substr(1, a.length - 2)) || 0];
});
};
}
// usage
console.log({0} world.format(hello));.as-console-wrapper { top: 0; max-height: 100% !important; }[Update 2020]
It's not that fashionable anymore to extend native objects. Although I don't oppose it (if used carefully) a format-function can do exactly the same, or you can use es20xx template literals (see MDN).
// no native String extension
const someValue = 100;
const otherValue = 555;
const format = (str2Format, ...args) =>
str2Format.replace(/({d+})/g, a => args[+(a.substr(1, a.length - 2)) || 0] );
console.log(format(someValue = {0}, otherValue = {1}, someValue, otherValue));
// template literal
console.log(`someValue = ${someValue}, otherValue = ${otherValue}`);.as-console-wrapper { top: 0; max-height: 100% !important; }
