demo: typescript playground demo 主要代码: interface Example { children?: Example[] } const example: Example = { children: [{ children: [] }] } if (example.children) { for (let i = 0; i < example.children.length; i++) { if (example.children[i] && example.children[i].children)...
The error "Variable is used before being assigned" occurs when we declare a variable without assigning a value to it or we only assign a value if a condition is met. To solve the error, change the variable's type to possibly undefined or give it an initial value. ...
typescript中if判断非空的变量依然会被报错variable is possibly undefined var item = example.children[i];if (item.children) { console.log(item.children.length)} 这里已经是底线啦~
BugA bug in TypeScript on Dec 28, 2016 @Aides359 From my point of view allowing it is strictly a bad thing. You've declared the type of the variable to benumberand then compare it toundefined. That's dead code by my definition. If it was allowed I'd have been really disappointed....
I'd expect to seevalueas the button text with these changes. This is the same issue we're experiencing in our code base. I know that everything is fine in@storybook/vue@6.1.21. Confirmed. Starting from Storybook v6.2, Args without a value are set tonull, notundefined. I couldn't ...