js中RegEx中的匹配模式答案

【问题标题】：match pattern in RegEx in jsjs中RegEx中的匹配模式
【发布时间】：2020-11-07 19:37:09
【问题描述】：

我想编辑一个 pattern 来检查文本是否以 number/s 开头并以 number/s 或 operator 结尾 并根据 test() 方法返回 true 或 false。

如何使用 JavaScript 做到这一点？`

var str= "123+125",str2 = "123",str3 = "123*";
let RegularExpression = /^\d*(\d*|(\+|\-|\*|\/){1,})$/; //this pattern variable what I want to edit because it doesn't do what I want. 
let result1 = RegularExpression.test(str);
let result2 = RegularExpression.test(str);
let result2 = RegularExpression.test(str);

【问题讨论】：

欢迎来到 StackOverflow。目前还不清楚您希望您的正则表达式匹配什么，以及您如何测试它，例如您没有使用str2 和str3 变量，而是绑定了result2 两次。或许可以考虑查看一些关于 JS 中正则表达式的文档，参见例如developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

标签： javascript php html regex dom

【解决方案1】：

使用

/^\d+([-+*\/]\d+)*[-+*\/]?$/

见proof

解释：

NODE                     EXPLANATION
--------------------------------------------------------------------------------
  ^                        the beginning of the string
--------------------------------------------------------------------------------
  \d+                      digits (0-9) (1 or more times (matching
                           the most amount possible))
--------------------------------------------------------------------------------
  (                        group and capture to \1 (0 or more times
                           (matching the most amount possible)):
--------------------------------------------------------------------------------
    [-+*\/]                  any character of: '-', '+', '*', '\/'
--------------------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
  )*                       end of \1 (NOTE: because you are using a
                           quantifier on this capture, only the LAST
                           repetition of the captured pattern will be
                           stored in \1)
--------------------------------------------------------------------------------
  [-+*\/]?                 any character of: '-', '+', '*', '\/'
                           (optional (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string

JavaScript：

var str= "123+125",str2 = "123",str3 = "123*";
let RegularExpression = /^\d+([-+*\/]\d+)*[-+*\/]?$/;
console.log( RegularExpression.test(str) );
console.log( RegularExpression.test(str2) );
console.log( RegularExpression.test(str3) );

【讨论】：

【解决方案2】：

您可以使用重复 1 次或多次匹配 1 个或多个数字，可选地后跟一个运算符。

^(?:\d+[+*/-]?)+

说明

^ 字符串开始
(?:非捕获组
- \d+[+*/-]? 匹配 1+ 位可选地后跟 + * / -
)+关闭非捕获组并重复1次以上

Regex demo

let pattern = /^(?:\d+[+*/-]?)+$/m;
[
  "123+125",
  "",
  "123",
  "123*",
  "123+125-1"
].forEach(s => console.log(s + " --> " + pattern.test(s)));

【讨论】：

【解决方案3】：

试试这个模式/^(\d*|[+/*-]?){1,}$/

var str= "123+125",str2 = "123",str3 = "123*";
let RegularExpression = /^(\d*|[+/*-]?){1,}$/; //this pattern variable what I want to edit because it doesn't do what I want. 
let result1 = RegularExpression.test(str);
let result2 = RegularExpression.test(str);
let result3 = RegularExpression.test(str);

console.log("res1:",result1,",res3:",result2,",res3:",result3)

【讨论】：