【Q089】vue 中 v-if 和 v-show 的区别是什么

[shfshanyue]

No description provided.

[zhaofeihao]

v-show always compiles and renders everything - it simply adds the "display: none" style to the element. It has a higher initial load cost, but toggling is very cheap.
Incomparison, v-if is truely conditional: it is lazy, so if its initial condition is false, it won't even do anything. This can be good for initial load time. When the condition is true, v-if will then compile and render its content. Toggling a v-if block actually tearsdown everything inside it, e.g. Components inside v-if are acually destroyed and re-created when toggled, so toggling a huge v-if block can be more expensive than v-show.

v-show 总是会进行编译和渲染的工作 - 它只是简单的在元素上添加了 display: none; 的样式。v-show 具有较高的初始化性能成本上的消耗，但是使得转换状态变得很容易。
相比之下，v-if 才是真正「有条件」的：它的加载是惰性的，因此，若它的初始条件是 false，它就不会做任何事情。这对于初始加载时间来说是有益的，当条件为 true 时，v-if 才会编译并渲染其内容。切换 v-if 下的块儿内容实际上时销毁了其内部的所有元素，比如说处于v-if下的组件实际上在切换状态时会被销毁并重新生成，因此，切换一个较大v-if块儿时会比v-show消耗的性能多。