Assigning to globals in strict mode

Oliver Hunt oliver at
Sun Oct 17 14:56:15 PDT 2010

I'm just in the process of making jsc produce the correct error in strict mode when assigning to an undefined priority, and I just want to verify my understanding of the spec (which is somewhat confused by multiple people stating that in strict mode the assignment operator can never create a new global property).

Per section 11.13.1 an implementation should throw a syntax error if LeftHandSideExpression evaluates to an unresolvable reference, which means

"use strict"; undeclared = (this.undeclared = 5);

Should throw as |undeclared| will not exist when LeftHandSideExpression is evaluated.


"use strict"; this.declared = 5; declared = (delete declared, 5);

Will not throw, but instead will recreate the |declared| property.

I'm simply wanting to verify my interpretation of the spec prior to fixing this bug.


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