Function cannot be accessed following the execution of eval()

Question

Function cannot be accessed following the execution of eval()

For some unknown reason, I need to utilize the eval() function and access a specific function called foo. Unfortunately, I am struggling to achieve this in TypeScript.

eval("function foo() { console.log(\"foo bar\") }");
// @ts-ignore
foo();

Instead of printing "foo bar" in the console log, the code above throws an error.

VM42:4 Uncaught ReferenceError: foo is not defined

You can experiment with the code snippet here.

However, the same code works perfectly fine in JavaScript.

Do you think additional configuration is needed?

javascript typescript tsconfig

Answer 1

Answer №1

One of the main restrictions imposed by TypeScript's implicit "use strict" is on the use of eval, specifically its inability to create new symbols. To work around this, you must explicitly return and assign the function from within the eval:

"use strict"

const bar = eval("function bar() { console.log(\"bar foo\") }; bar;");

bar();

Answer 2

One of the main restrictions imposed by TypeScript's implicit "use strict" is on the use of eval, specifically its inability to create new symbols. To work around this, you must explicitly return and assign the function from within the eval:

"use strict"

const bar = eval("function bar() { console.log(\"bar foo\") }; bar;");

bar();

Answer 3

Answer №2

// To make a function accessible globally, you can define it in the window/global object.

// You have the option to "hoist" a function using a cheat method.

let foo;
eval('function foo() { console.log("foo bar") };');

// @ts-ignore
foo();

// For browser compatibility, add the function to the window object.

eval("function foo() { console.log(\"foo bar\") }; window.foo = foo");

// @ts-ignore
foo();

// For node.js compatibility, add the function to the global object.

eval("function foo() { console.log(\"foo bar\") }; global.foo = foo");

// @ts-ignore
foo();

Answer 4

// To make a function accessible globally, you can define it in the window/global object.

// You have the option to "hoist" a function using a cheat method.

let foo;
eval('function foo() { console.log("foo bar") };');

// @ts-ignore
foo();

// For browser compatibility, add the function to the window object.

eval("function foo() { console.log(\"foo bar\") }; window.foo = foo");

// @ts-ignore
foo();

// For node.js compatibility, add the function to the global object.

eval("function foo() { console.log(\"foo bar\") }; global.foo = foo");

// @ts-ignore
foo();

Function cannot be accessed following the execution of eval()

Answer №1

Answer №2

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