Javascript：未定义字符串的格式
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Javascript: string's format is not defined
提问by navyad
I have following snippet of javascript code:
我有以下javascript代码片段：
var someValue = 100;
var anotherValue = 555;
alert('someValue is {0} and anotherValue is {1}'.format(someValue, anotherValue));
getting following error:
收到以下错误：
Uncaught TypeError: undefined is not a function
what am i missing, here ?
我错过了什么，在这里？
回答by KooiInc
String.formatis not a native Stringextension. It's pretty easy to extend it yourself:
String.format不是本机String扩展。自己扩展它很容易：
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]
[ 2020 年更新]
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).
扩展原生对象不再那么流行了。虽然我不反对它（如果小心使用）format- 函数可以完全相同，或者您可以使用 es20xx template literals（请参阅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; }回答by Ortal Blumenfeld Lagziel
String.format = function() {
var s = arguments[0];
for (var i = 0; i < arguments.length - 1; i += 1) {
var reg = new RegExp('\{' + i + '\}', 'gm');
s = s.replace(reg, arguments[i + 1]);
}
return s;
};
var strTempleate = String.format('hello {0}', 'Ortal');
