NodeJS SyntaxError: Unexpected token '.'

Question

Node JS 和 NPM 的初学者。以下代码抛出语法错误，无法解决问题。

节点版本：v12.18.3 NPM 版本：7.15.1

错误

LayerObj.options?.["displayName"] != undefined
                       ^

SyntaxError: Unexpected token '.'
    at wrapSafe (internal/modules/cjs/loader.js:1053:16)
    at Module._compile (internal/modules/cjs/loader.js:1101:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)
    at Module.load (internal/modules/cjs/loader.js:985:32)
    at Function.Module._load (internal/modules/cjs/loader.js:878:14)
    at Module.require (internal/modules/cjs/loader.js:1025:19)
    at require (internal/modules/cjs/helpers.js:72:18)
    at Object.<anonymous> (/Applications/MAMP/htdocs/nft-generators/hashlips_art_engine-main/index.js:2:39)
    at Module._compile (internal/modules/cjs/loader.js:1137:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)

代码

const layersSetup = (layersOrder) => {
  const layers = layersOrder.map((layerObj, index) => ({
    id: index,
    elements: getElements(`${layersDir}/${layerObj.name}/`),
    name:
      layerObj.options?.["displayName"] != undefined
        ? layerObj.options?.["displayName"]
        : layerObj.name,
    blend:
      layerObj.options?.["blend"] != undefined
        ? layerObj.options?.["blend"]
        : "source-over",
    opacity:
      layerObj.options?.["opacity"] != undefined
        ? layerObj.options?.["opacity"]
        : 1,
    bypassDNA:
      layerObj.options?.["bypassDNA"] !== undefined
        ? layerObj.options?.["bypassDNA"]
        : false,
  }));
  return layers;
};

Answer 1

Optional chaining (?.) 是在 Node.js 14 中添加的，在节点 12 中 不直接可用。

The ?. operator is like the . chaining operator, except that instead of causing an error if a reference is nullish (null or undefined), the expression short-circuits with a return value of undefined. When used with function calls, it returns undefined if the given function does not exist.

使用更新版本的 Node 或使用 Node 12 兼容代码。

New JS features in Node.js v14.0 讨论了 Node 14 中的一些新语言结构。

NodeJS SyntaxError: Unexpected token '.'

NodeJS SyntaxError: Unexpected token '.'

node.js

npm