英文:
Different Results when assigning an expression to a variable and running it in the JavaScript REPL environment
问题
我目前正在尝试深入理解JavaScript类型转换。在使用node REPL环境时，我遇到了语句[]+{}和let x = []+{}。执行第二个语句后，变量x的值为undefined，尽管我预期这两个语句的表达式都应该评估为'[object Object]'。
是什么导致了这种差异？
英文:
I am currently trying to develop a deeper understanding of JavaScript type coercion. While playing around with the node REPL environment, I encountered the statements []+{} and let x = []+{}. After executing the second statement, the variable x holds the value undefined, although I expected that the expression evaluates to '[object Object]' in both statements.
What causes this difference?
答案1
得分: 1
这是因为 let 语句返回 undefined，而不是变量值。要检索变量值，您必须键入变量名称。
let x = [] + {};
// undefined
x;
// " [object Object] "
英文:
That's because let statement returns undefined, not variable value. To retrieve variable value, you have to type the variable name.
let x = [] + {};
// undefined
x;
// "[object Object]"
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