Javascript 正则表达式 - 9 位数字
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Javascript Regex - 9-digit number
提问by Dan
I am trying to validate a variable contains a 9-digit number in Javascript. This should be basic but for some reason this is failing:
我正在尝试在 Javascript 中验证包含 9 位数字的变量。这应该是基本的，但由于某种原因，这是失败的：
var test = "123123123";
var pattern = new RegExp("/\d{9}/");
if(test.match(pattern))
{
//This code never executes
}
else
{
//This code is always executing
alert('no match!');
}
Can anyone see why I am not getting a match?
谁能明白为什么我没有得到匹配？
I also tried type-casting test to an integer with:
我还尝试对整数进行类型转换测试：
test = Number(test);
...but this doesn't work as it has to be a String to support the .match method.
...但这不起作用，因为它必须是一个字符串才能支持 .match 方法。
回答by Matt Ball
You're mixing the two different regex constructors. Pick one:
您正在混合两种不同的正则表达式构造函数。选一个：
var pattern = new RegExp("^\d{9}$");
// or
var pattern = /^\d{9}$/;
N.B.you probably want to add start and end anchors (as above) to make sure the wholestring matches.
注意您可能想要添加开始和结束锚点（如上）以确保整个字符串匹配。
回答by vcsjones
You are mixing regex literal syntaxwith the RegExp class. Try:
您正在将regex 文字语法与 RegExp 类混合。尝试：
var test = "123123123";
var pattern = /\d{9}/;
if(test.match(pattern))
{
alert('match!');
//This code never executes
}
else
{
//This code is always executing
alert('no match!');
}?
Additionally, you may want to change your regex to match on the beginning and end of line if you want to ensure it contains onlya 9 digit number. Right now the regex will match any string that contains a 9 digit number. You would change it like so:
此外，你可能想改变你的正则表达式匹配的开始，如果你想确保它包含了行结束只有9位数字。现在正则表达式将匹配任何包含 9 位数字的字符串。你会像这样改变它：
var pattern = /^\d{9}$/;
回答by J?rg W Mittag
You aren't looking for 9 consecutive digits, you are looking for 9 consecutive digits enclosed in slashes.
您不是在寻找 9 个连续数字，而是在寻找包含在 slashes 中的9 个连续数字。
回答by Michael Berkowski
When using a new Regexp()constructor, you should not include the /delimieters, since they are treated as literals in the expression.
使用new Regexp()构造函数时，不应包含/分隔符，因为它们在表达式中被视为文字。
Also your expression should be anchored ^$to ensure it contains no other characters than the nine digits.
此外，您的表达式应该被锚定^$以确保它不包含九位数字以外的其他字符。
var test = "123123123";
// \d would need to be escaped as \d in RegExp()
var pattern = new RegExp("^\d{9}$");
// ..Or...
var pattern = new RegExp("^[0-9]{9}$");
Using a regular expression literal without new Regexp()is often a better strategy if you don't need to do string manipulations or include variables in the regex, since it avoids the extra backslash-escaping.
new Regexp()如果您不需要进行字符串操作或在正则表达式中包含变量，则使用正则表达式文字通常是更好的策略，因为它避免了额外的反斜杠转义。
var pattern = /^\d{9}$/;
回答by Stefan Seemayer
Try removing the slashes and escaping the backslash:
尝试删除斜杠并转义反斜杠：
var test = "123123123";
var pattern = new RegExp("\d{9}");
if(test.match(pattern))
{
//This code never executes
alert("match");
}
else
{
//This code is always executing
alert('no match!');
}
