JavaScript eval Execution Process

When Eval is performed, the following procedure is performed for eval (x):

1. If the type of x is not a string, it will return x;

2. Convert x to ECMAScript code. If the conversion fails, blame throws the SyntaxError exception.

3. Create a new execution context for the converted code and deposit the EVALCTX;

4. Execute the converted code and save the results to result;

5. Exit Evalctx execution context, and reply to the execution environment of the previous step.

6. If Result.type is normal, if his return value is non-null, then the eval will return v;

7 If Result.type is normal, if his return value is empty, then the undefined will be returned;

8. Otherwise, you must throw an exception for Result.type

JavaScript eval Execution Process