Sometimes, we may run into the ‘SyntaxError: "use strict" not allowed in function with non-simple parameters’ when we’re developing JavaScript apps.
In this article, we’ll look at how to fix the ‘SyntaxError: "use strict" not allowed in function with non-simple parameters’ when we’re developing JavaScript apps.
Fix the ‘SyntaxError: "use strict" not allowed in function with non-simple parameters’ When Developing JavaScript Apps
To fix the ‘SyntaxError: "use strict" not allowed in function with non-simple parameters’ when we’re developing JavaScript apps, we should make sure we don’t add the 'use strict' directive inside a function that uses default parameters, rest parameters, or destructuring parameters.
In Edge, the error message for this error is Cannot apply strict mode on functions with non-simple parameter list .
In Firefox, the error message for this error is SyntaxError: "use strict" not allowed in function with default parameter, SyntaxError: "use strict" not allowed in function with rest parameter, and SyntaxError: "use strict" not allowed in function with destructuring parameter.
And in Chrome, the error message for this error is SyntaxError: Illegal 'use strict' directive in function with non-simple parameter list.
For instance, we shouldn’t write code like:
const sum = (a = 1, b = 2) => {
'use strict';
return a + b;
}
Instead, we should put 'use strict' before the function:
"use strict";
const sum = (a = 1, b = 2) => {
return a + b;
};
Conclusion
To fix the ‘SyntaxError: "use strict" not allowed in function with non-simple parameters’ when we’re developing JavaScript apps, we should make sure we don’t add the 'use strict' directive inside a function that uses default parameters, rest parameters, or destructuring parameters.
In Edge, the error message for this error is Cannot apply strict mode on functions with non-simple parameter list .
In Firefox, the error message for this error is SyntaxError: "use strict" not allowed in function with default parameter, SyntaxError: "use strict" not allowed in function with rest parameter, and SyntaxError: "use strict" not allowed in function with destructuring parameter.
And in Chrome, the error message for this error is SyntaxError: Illegal 'use strict' directive in function with non-simple parameter list.
