在了解 JavaScript 的特性时,我在同一个函数中使用了默认参数和扩展语法。
let whatIsThis = (a, b = 2, ...c) => {
console.log("a = " + a, "b = " + b,"c = " + c)
}
whatIsThis(a = 1, c = [2,3,4,5,6,7,8])
运行后,我预计输出是这样的:
"a = 1"
"b = 2"
"c = 2,3,4,5,6,7,8"
但我却得到了这个:
"a = 1"
"b = 2,3,4,5,6,7,8"
"c = "
为什么这不起作用?
最佳答案
这是因为您不能将命名参数传递给 JavaScript 中的函数。当你执行 whatIsThis(a = 1, c = [2,3,4,5,6,7,8]) 时,它的真正含义是 whatIsThis(1, [2,3,4,5,6,7,8 ])(因为 a = 1 语句返回 1)。
您可以做的是将默认参数移到末尾(这通常是一个好习惯)或将您的参数包装在对象中。例如
let whatIsThis = ({a, b = 2, c}) => {
console.log("a = " + a, "b = " + b,"c = " + c)
}
whatIsThis({a: 1, c: [2,3,4,5,6,7,8]})
关于javascript - 在 ES6 中使用默认值和扩展语法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/51962959/