正则表达式从字符串中获取所有 JavaScript 变量名称和值

Question

say I have the following string:

let code = `
      var x = 4;
      var y=9,
          w=8
      var z=8080
      other()
      x=12

`

How do I write a regex that gets all of the variable declarations? In this case, I want to return all statements, and no expressions, so exclude the other() and x=12 part. So far I have

 let results = ` var x = 4; var y=9, w=8 var z=8080 other() x=12 `.match(/(var)(.*?)(;|,|\n)/g); console.log(results);

But I couldn't figure out how to include the w=8 part also, since that's also a declaration statement, while excluding the expressions. I tried .match(/(var|\n)(.*?)(;|,|\n)/g) but that also returns x=12, which I don't want. I need to also return all statement blocks even if there is a comma right before it (either on a previous line, or previous character, anything that would normally allow a variable declaration).

Any idea how to do this with regex?

EDIT:

with uglifyjs I'm able to do the following (which is the result I want):

 let strin = ` var x = 4; var y=9, w=8, kk = { ok:1234 }, p, a = undefined var z=8080 other() x=12 ` let results = UglifyJS.parse(strin).body.filter(x=>x.__proto__.TYPE == "Var").map(x=> x.definitions.map(y=>({ name:y.name.name, value:y.value? findInPos(y.value.start, y.value.end,strin): undefined })), ).flat() function findInPos(start, end,str) { return str.substring( start.pos, end.endpos ); }

 <script type="text/javascript" src="https://yaakovyitzchak.github.io/coby/uglify.js"> </script>

But it seems a bit overkill just to extract the string value of each variable? (I don't need to evaluate it, just get the string value like so)

Answer 1

The task can be nicely solved with TypeScript Compiler API, as it can parse not only TypeScript but JavaScript code too. Since TypeScript compiles into JavaScript - there should be no problem to integrate the following TS snippet into a JS project.

See demo

import ts from "typescript";

const code = `
    var x = 4;
    var y=9,
        w=8
    var z=8080
    other()
    x=12
`;

const sf = ts.createSourceFile(
    "test.js",
    code,
    ts.ScriptTarget.ES2017,
    true,
    ts.ScriptKind.JS,
);

sf.forEachChild((n) => {
    if (ts.isVariableStatement(n)) {
        n.declarationList.declarations.forEach((decl) => {
            const name = decl.name.getText();
            const value = decl.initializer?.getText();
            console.log(`${name} = ${value}`);
        });
    }
});

The code above prints the following output to console:

x = 4
y = 9
w = 8
z = 8080