String.Format in javascript

// String.js - liberated from MicrosoftAjax.js on 03/28/10 by Sky Sanders /*
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IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</textarea>
*/(function(window) { $type = String;
$type.__typeName = 'String';
$type.__class = true; $prototype = $type.prototype;
$prototype.endsWith = function String$endsWith(suffix) {
/// <summary>Determines whether the end of this instance matches the specified string.</summary>
/// <param name="suffix" type="String">A string to compare to.</param>
/// <returns type="Boolean">true if suffix matches the end of this instance; otherwise, false.</returns>
return (this.substr(this.length - suffix.length) === suffix);
} $prototype.startsWith = function String$startsWith(prefix) {
/// <summary >Determines whether the beginning of this instance matches the specified string.</summary>
/// <param name="prefix" type="String">The String to compare.</param>
/// <returns type="Boolean">true if prefix matches the beginning of this string; otherwise, false.</returns>
return (this.substr(0, prefix.length) === prefix);
} $prototype.trim = function String$trim() {
/// <summary >Removes all leading and trailing white-space characters from the current String object.</summary>
/// <returns type="String">The string that remains after all white-space characters are removed from the start and end of the current String object.</returns>
return this.replace(/^\s+|\s+$/g, '');
} $prototype.trimEnd = function String$trimEnd() {
/// <summary >Removes all trailing white spaces from the current String object.</summary>
/// <returns type="String">The string that remains after all white-space characters are removed from the end of the current String object.</returns>
return this.replace(/\s+$/, '');
} $prototype.trimStart = function String$trimStart() {
/// <summary >Removes all leading white spaces from the current String object.</summary>
/// <returns type="String">The string that remains after all white-space characters are removed from the start of the current String object.</returns>
return this.replace(/^\s+/, '');
} $type.format = function String$format(format, args) {
/// <summary>Replaces the format items in a specified String with the text equivalents of the values of corresponding object instances. The invariant culture will be used to format dates and numbers.</summary>
/// <param name="format" type="String">A format string.</param>
/// <param name="args" parameterArray="true" mayBeNull="true">The objects to format.</param>
/// <returns type="String">A copy of format in which the format items have been replaced by the string equivalent of the corresponding instances of object arguments.</returns>
return String._toFormattedString(false, arguments);
} $type._toFormattedString = function String$_toFormattedString(useLocale, args) {
var result = '';
var format = args[0]; for (var i = 0; ; ) {
// Find the next opening or closing brace
var open = format.indexOf('{', i);
var close = format.indexOf('}', i);
if ((open < 0) && (close < 0)) {
// Not found: copy the end of the string and break
result += format.slice(i);
break;
}
if ((close > 0) && ((close < open) || (open < 0))) { if (format.charAt(close + 1) !== '}') {
throw new Error('format stringFormatBraceMismatch');
} result += format.slice(i, close + 1);
i = close + 2;
continue;
} // Copy the string before the brace
result += format.slice(i, open);
i = open + 1; // Check for double braces (which display as one and are not arguments)
if (format.charAt(i) === '{') {
result += '{';
i++;
continue;
} if (close < 0) throw new Error('format stringFormatBraceMismatch'); // Find the closing brace // Get the string between the braces, and split it around the ':' (if any)
var brace = format.substring(i, close);
var colonIndex = brace.indexOf(':');
var argNumber = parseInt((colonIndex < 0) ? brace : brace.substring(0, colonIndex), 10) + 1; if (isNaN(argNumber)) throw new Error('format stringFormatInvalid'); var argFormat = (colonIndex < 0) ? '' : brace.substring(colonIndex + 1); var arg = args[argNumber];
if (typeof (arg) === "undefined" || arg === null) {
arg = '';
} // If it has a toFormattedString method, call it. Otherwise, call toString()
if (arg.toFormattedString) {
result += arg.toFormattedString(argFormat);
}
else if (useLocale && arg.localeFormat) {
result += arg.localeFormat(argFormat);
}
else if (arg.format) {
result += arg.format(argFormat);
}
else
result += arg.toString(); i = close + 1;
} return result;
}})(window);