反转if语句

Question

我理解if条件是如何工作的。像这样：

if (condition) {
    block of code to be executed if the condition is true
}

但我如何反转，例如如果声明正确，不要触发这行代码？

if $("span:contains('399')) {
    block of code to be executed if the condition is false
}

Answer 1

if (!condition) {
    block of code to be executed if the condition is false
}