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//let也不允许同一个块作用域中出现冗余声明。这样会导致报错 | |
var name; | |
var name; | |
let age; | |
let age; // SyntaxError;标识符age已经声明过了 | |
//JavaScript引擎会记录用于变量声明的标识符及其所在的块作用域,因此嵌套使用相同的标识符不会报错,而这是因为同一个块中没有重复声明: | |
var name = 'Nicholas'; |