Bug 136445 – Assignment to a property on a primitive in strict mode should not throw

• Component: JavaScriptCore
• Status: RESOLVED INVALID

[Jordan Harband]

`(function () { "use strict"; 3.0.a = true; }())`
`(function () { "use strict"; 'foo'.a = true; }())`
`(function () { "use strict"; true.a = true; }())`

None of these throw exceptions in Chrome, Firefox, Opera - but in Safari 7.1, these all throw a TypeError "Attempted to assign to readonly property.".

According to the ES5 spec ( https://es5.github.io/#C ) and ES6 spec ( https://people.mozilla.org/~jorendorff/es6-draft.html#sec-strict-mode-of-ecmascript ), Safari is in error here. In addition, one of the TC39 spec maintainers confirmed via Twitter that this is a Safari bug ( https://twitter.com/awbjs/status/506687103506587648 )

Steps to Reproduce:
Run any of the JS functions in the console, or any other JS mechanism:

(function () { "use strict"; 3.0.a = true; }())

(function () { "use strict"; 'foo'.a = true; }())

(function () { "use strict"; true.a = true; }())

[Jordan Harband]

Sorry for the noise - turns out Safari is the only browser doing this correctly. https://twitter.com/awbjs/status/506845194025594881

https://code.google.com/p/v8/issues/detail?id=3088 and https://bugzilla.mozilla.org/show_bug.cgi?id=779682