JavaScript-String类库
~~~
// String.js - liberated from MicrosoftAjax.js on 03/28/10 by Sky Sanders
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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*/
(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);
~~~
用例
~~~
<script src="script/string.js" type="text/javascript"></script>
<script type="text/javascript">
var a = String.format("Hello {0}!", "world");
alert(a);
</script>
~~~
#### String.Format in JavaScript
~~~
<html>
<head>
<title>JavaScript String.Format</title>
<script type="text/javascript">
// This is the function.
String.prototype.format = function (args) {
var str = this;
return str.replace(String.prototype.format.regex, function(item) {
var intVal = parseInt(item.substring(1, item.length - 1));
var replace;
if (intVal >= 0) {
replace = args[intVal];
} else if (intVal === -1) {
replace = "{";
} else if (intVal === -2) {
replace = "}";
} else {
replace = "";
}
return replace;
});
};
String.prototype.format.regex = new RegExp("{-?[0-9]+}", "g");
// Sample usage.
var str = "She {1} {0}{2} by the {0}{3}. {-1}^_^{-2}";
str = str.format(["sea", "sells", "shells", "shore"]);
alert(str);
</script>
</head>
</html>
~~~
Save the above to an HTML file and run it in your browser. You will see a dialog that says:
~~~
She sells seashells by the seashore. {^_^}
~~~
参考资料：https://www.codeproject.com/Tips/201899/String-Format-in-JavaScript
