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  • Levine Veblen thinks this is interesting:

(The concatenation of the parentheses around the JSON text is a workaround for an ambiguity in JavaScript's grammar.)

From

Cover of JavaScript: The Good Parts

Note

eval中另外增加的'(' + ')' 为了防止语法歧义,有点类似于宏中对于参数添加()的用法一样