如何用Babel.js将导入语句插入到AST中？

  • Z时代
  • 2024-01-10
  • 分类：问答

我试图插入一个导入声明成JavaScript代码段与Babel.js：如何用Babel.js将导入语句插入到AST中？

const babel = require('babel-core')  
const t = babel.types  
const traverse = babel.traverse  
const template = babel.template  
const generate = require('babel-generator').default  
const babylon = require('babylon')  
const code = [  
    "import A from 'a'",  
    "import B from 'b'",  
    "export default {",  
    " components: {",  
    " },",  
    " methods: {",  
    " init() {",  
    " }",  
    " }",  
    "}"  
].join("\n")  
console.log(code)  
const ast = babylon.parse(code, {  
    sourceType: 'module'  
})  
var n = []  
traverse(ast, {  
    ImportDeclaration: {  
    exit(path) {  
     n.push(path)  
    }  
    }  
})  
const name = 'UserDialog',  
    src = './user-dialog.vue'  
if (n.length) {  
    const importCode = "import " + name + " from '" + src + "'"  
    console.log(importCode)  
    const importAst = template(importCode, {  
    sourceType: 'module'  
    })()  
    // append to last import statement  
    n[n.length - 1].insertAfter(importAst);  
    console.log(generate(ast).code)  
}

但我得到了以下错误

有什么正确的方法来做到这一点？

FYI： 你可以得到上面的代码从git clone https://github.com/aztack/babel-test.git

回答：

你最好还是写信以此为巴贝尔的插件，例如

const babel = require('babel-core'); 
const code = [ 
    "import A from 'a'", 
    "import B from 'b'", 
    "export default {", 
    " components: {", 
    " },", 
    " methods: {", 
    " init() {", 
    " }", 
    " }", 
    "}" 
].join("\n"); 
const result = babel.transform(code, { 
    plugins: [myImportInjector] 
}); 
console.log(result.code); 
function myImportInjector({ types, template }) { 
    const myImport = template(`import UserDialog from "./user-dialog";`, {sourceType: "module"}); 
    return { 
    visitor: { 
     Program(path, state) { 
     const lastImport = path.get("body").filter(p => p.isImportDeclaration()).pop(); 
     if (lastImport) lastImport.insertAfter(myImport()); 
     }, 
    }, 
    }; 
}

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