我正在编写一段客户端 JavaScript 代码，它接受一个函数并找到它的导数，但是，应该与幂规则匹配的正则表达式无法在 JavaScript 程序的上下文中工作，甚至尽管与独立的正则表达式测试器一起使用时它会成功匹配。
目前代码非常简单，我计划 flesh it out稍后。
我执行此操作的浏览器是 Midori，操作系统是 Ubuntu 10.04 (Lucid Lynx)。除了代码之外，下面是用作界面的 HTML 页面:
页面:
<html>
<head>
<title>
Derivative Calculator
</title>
<script type="text/javascript" src="derivative.js">
</script>
<body>
<form action="" name=form>
<input type=text name=f /> with respects to
<input type=text name=vr size=7 />
<input type=button value="Derive!" onClick="main(this.form)" /> <br />
<input type=text name=result value="" />
</form>
</body>
</html>
derivative.js:
function main(form) {
form.result.value = derive(form.f.value, form.vr.value);
}
function derive(f, v) {
var atom = [];
atom["sin(" + v + ")"] = "cos(" + v + ")";
atom["cos(" + v + ")"] = "-sin(" + v + ")";
atom["tan(" + v + ")"] = "sec^(2)(" + v + ")";
atom["sec(" + v + ")"] = "sec(" + v + ")*tan(" + v + ")";
atom["1/(cos(" + v + "))"] = "sec(" + v + ")*tan(" + v + ")";
atom["csc(" + v + ")"] = "-csc(" + v + ")*cot(" + v + ")";
atom["1/(sin(" + v + "))"] = "-csc(" + v + ")*cot(" + v + ")";
atom["cot(" + v + ")"] = "-csc^(2)(" + v + ")";
atom["1/(tan(" + v + "))"] = "-csc^(2)(" + v + ")";
atom["sin^(-1)(" + v + ")"] = "1/sqrt(1 - " + v + "^(2))";
atom["arcsin(" + v + ")"] = "1/sqrt(1 - " + v + "^(2))";
atom["cos^(-1)(" + v + ")"] = "-1/sqrt(1 - " + v + "^(2))";
atom["arccos(" + v + ")"] = "-1/sqrt(1 - " + v + "^(2))";
atom["tan^(-1)(" + v + ")"] = "1/(1 + " + v + "^(2))";
atom["arctan(" + v + ")"] = "1/(1 + " + v + "^(2))";
atom["sec^(-1)(" + v + ")"] = "1/(|" + v + "|*sqrt(" + v + "^(2) - 1))";
atom["arcsec(" + v + ")"] = "1/(|" + v + "|*sqrt(" + v + "^(2) - 1))";
atom["csc^(-1)(" + v + ")"] = "-1/(|" + v + "|*sqrt(" + v + "^(2) - 1))";
atom["arccsc(" + v + ")"] = "-1/(|" + v + "|*sqrt(" + v + "^(2) - 1))";
atom["cot^(-1)(" + v + ")"] = "-1/(1 + " + v + "^(2))";
atom["arccot(" + v + ")"] = "-1/(1 + " + v + "^(2))";
atom["ln(" + v + ")"] = "1/(" + v + ")";
atom["e^(" + v + ")"] = "e^(" + v + ")";
atom["ln(|" + v + "|)"] = "1/(" + v + ")";
atom[v] = "1";
var match = "";
if (new Boolean(atom[f]) == true) {
return atom[f];
} else if (f.match(/^[0-9]+$/)) {
return "";
} else if (f.match(/([\S]+)([\s]+)\+([\s]+)([\S]+)/)) {
match = /([\S]+)([\s]+)\+([\s]+)([\S]+)/.exec(f);
return derive(match[1], v) + " + " + derive(match[4], v);
} else if (f.match(new RegExp("^([0-9]+)(" + v + ")$"))) {
match = new RegExp("^([0-9]+)(" + v + ")$").exec(f);
return match[1];
} else if (f.match(new RegExp("^([0-9]+)(" + v + ")\^([0-9]+)$"))) {
match = new RegExp("^([0-9]+)(" + v + ")\^([0-9]+)$").exec(f);
return String((match[1] * (match[3]))) + v + "^" +
String(match[3] - 1);
} else {
return "?";
}
}
特别是，我在使用这种模式时遇到了麻烦:
} else if (f.match(new RegExp("^([0-9]+)(" + v + ")\^([0-9]+)$"))) {
match = new RegExp("^([0-9]+)(" + v + ")\^([0-9]+)$").exec(f);
return String((match[1] * (match[3]))) + v + "^" +
String(match[3] - 1);
最佳答案
您需要双重转义插入符号:
")\\^([0-9]+)$"
否则 javascript 不会将反斜杠解释为反斜杠，因此永远不会转义正则表达式的插入符号。
关于javascript - JS 正则表达式不匹配，即使它与正则表达式测试器一起工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/3055129/