Detailed explanation of Vue3's sandbox mechanism

<div>{{test}}</div>
<div>{{Math.floor(1)}}</div>

const _Vue = Vue;

return function render(_ctx, _cache, $props, $setup, $data, $options) {
  with (_ctx) {
    const {
      toDisplayString: _toDisplayString,
      createVNode: _createVNode,
      Fragment: _Fragment,
      openBlock: _openBlock,
      createBlock: _createBlock,
    } = _Vue;

    return (
      _openBlock(),
      _createBlock(
        _Fragment,
        null,
        [
          _createVNode("div", null, _toDisplayString(test), 1 /* TEXT */),
          _createVNode(
            "div",
            null,
            _toDisplayString(Math.floor(1)),
            1 /* TEXT */
          ),
        ],
        64 /* STABLE_FRAGMENT */
      )
    );
  }
};

const GLOBALS_WHITE_LISTED =
  "Infinity,undefined,NaN,isFinite,isNaN,parseFloat,parseInt,decodeURI," +
  "decodeURIComponent,encodeURI,encodeURIComponent,Math,Number,Date,Array," +
  "Object,Boolean,String,RegExp,Map,Set,JSON,Intl,BigInt";

const isGloballyWhitelisted = (key) => {
  return GLOBALS_WHITE_LISTED.split(",").includes(key);
};

const hasOwn = (obj, key) => {
  return Object.prototype.hasOwnProperty.call(obj, key);
};

const origin = {};
const _ctx = new Proxy(origin, {
  get(target, key, receiver) {
    if (hasOwn(target, key)) {
      Reflect.get(target, key, receiver);
    } else {
      console.warn(
        `Property ${JSON.stringify(key)} was accessed during render ` +
          `but is not defined on instance.`
      );
    }
  },
  has(target, key) {
    // If it is a global object, return false, do not trigger get interception, and search for variables from the previous scope. // If it is not a global object, return true, trigger get interception. return !isGloballyWhitelisted(key);
  },
});

<div>{{test}}</div>
<div>{{Math.floor(1)}}</div>

import {
  toDisplayString as _toDisplayString,
  createVNode as _createVNode,
  Fragment as _Fragment,
  openBlock as _openBlock,
  createBlock as _createBlock,
} from "vue";

export function render(_ctx, _cache, $props, $setup, $data, $options) {
  return (
    _openBlock(),
    _createBlock(
      _Fragment,
      null,
      [
        _createVNode("div", null, _toDisplayString(_ctx.a), 1 /* TEXT */),
        _createVNode(
          "div",
          null,
          _toDisplayString(Math.floor(1)),
          1 /* TEXT */
        ),
      ],
      64 /* STABLE_FRAGMENT */
    )
  );
}

const GLOBALS_WHITE_LISTED =
  "Infinity,undefined,NaN,isFinite,isNaN,parseFloat,parseInt,decodeURI," +
  "decodeURIComponent,encodeURI,encodeURIComponent,Math,Number,Date,Array," +
  "Object,Boolean,String,RegExp,Map,Set,JSON,Intl,BigInt";

const isGloballyWhitelisted = (key) => {
  return GLOBALS_WHITE_LISTED.split(",").includes(key);
};
const isLiteralWhitelisted = (key)=>{
  return 'true,false,null,this'.split(',').includes(key)
}
export function processExpression(
  node
) {
  const rewriteIdentifier = (raw) => {
    return `_ctx.${raw}`
  }
  const rawExp = node.content
  if (isSimpleIdentifier(rawExp)) {
    const isAllowedGlobal = isGloballyWhitelisted(rawExp)
    const isLiteral = isLiteralWhitelisted(rawExp)
    if (!isAllowedGlobal && !isLiteral) {
      node.content = rewriteIdentifier(rawExp)
    }
    return node
  }