正則表達式匹配號碼出來的乳膠出來的乳膠

Question

正則表達式匹配號碼，我有這樣的"there is a LaTex is ${ \\frac{123}{456} }$ and a pure number 789 and another LaTex ${ 9^{n+1} }$" 我需要一個正則表達式來獲取數聲明，我不需要位於LaTeX的數字

Answer 1

你可以使用這個表達式：

/(?:^|\}\$)(?:.(?!\$\{))*?(\d+)/ 

說明：

(?:  # a non-capturing group 
    ^|\}\$ # either the beginning of the string, or a "}$" 
)   # this will make sure we're not currently in a LaTeX thingy 

(?:  # another non-capturing group 
    .  # any character 
    (?!\$\{) # not followed by a "${" (make sure we don't go into a LaTeX thingy) 
)*?  # repeated zero or more times 

(\d+)  # the number that you want! 

我假設你的緯度eX將形成良好;即你將不會有像${ 123 }$ }$ 456 ${ 789 }$這樣的帶有不匹配括號的字符串。

試試：

var regex = /(?:^|\}\$)(?:.(?!\$\{))*?(\d+)/; 
 
var str = 'there is a LaTex is ${ \\frac{123}{456} }$ and a pure number 789 and another LaTex ${ 9^{n+1} }$'; 
 
alert(str.match(regex)[1]);