JSLint will throw the "Missing 'use strict' statement" error when it encounters a function that does not contain the strict mode directive, and none of whose ancestor scopes contain the strict mode directive. JSHint will throw this error in the same situation, but only when the strict option is set to true. Here's an example of a function that does not run in strict mode:
A "use strict" statement is an example of a directive, which can appear as the first statement of a program or a function (ES5 §14.1):
A Directive Prologue is the longest sequence of ExpressionStatement productions occurring as the initial SourceElement productions of a Program or FunctionBody and where each ExpressionStatement in the sequence consists entirely of a StringLiteral token followed a semicolon. The semicolon may appear explicitly or may be inserted by automatic semicolon insertion. A Directive Prologue may be an empty sequence.
You can fix this error by simply adding a Use Strict directive to the function, or to an ancestor function:
In JSHint 1.0.0 and above you have the ability to ignore any warning with a special option syntax. This message is treated as an error by JSHint which means you are unable to prevent it from being issued.