Javascript 和正则表达式：未定义和“”

Question

我不太熟悉正则表达式，我遇到了以下问题：

当运行正则表达式拆分我的字符串时，我得到很多未定义和 "" 以及结果。我已经尝试使用“(?:”，这是我在 Whosebug 的另一个答案中看到的以及许多其他内容。然后我使用 array.filter 函数删除它们，但我不想那样做。谁能帮我？（并向我解释为什么会这样）。

let values = line.split(/(\!=)|(<=)|(>=)|(==)|(\/\/)|(\/\*)|(\*\/)|(")|(=)|(<)|(>)|(\+)|(-)|(\*)|(\)|(\()|(\))|;| /g);

return values.filter(value => {
    return value !== undefined && value !== "";
});

可以使用的字符串：

"int x = 7;" => ["int","x","=","7",";"]

"int x = 7 + 25 * 52" => ["int","x","=","7","+","25","*","52"]

"while( x != 0)" => ["while","(","x","!=","0",")"]

'if(idade > 70 && sexo == "masculino")' 
    => ["if","(","idade",">","70","&&","sexo","==",""masculino"",")"]

谢谢！

Answer 1

原因是每个备选方案都在其自己的捕获组中。只有真正匹配的捕获组才会被填入，其余为空。相反，将捕获组放在所有备选方案周围。

line = "#include <stdio.h>";
let values = line.split(/(\!=|<=|>=|==|\/\/|\/\*|\*\/|"|=|<|>|\+|-|\*|\|\(|\)|;| )/g);
console.log(values);

Javascript 和正则表达式：未定义和“”

Javascript and Regex: undefined and ""

javascript

regex

regex-group