反向if語句

Question

我瞭解if條件如何工作。像這樣：

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

但是，如何反轉例如如果陳述是正確的，不要觸發這行代碼？

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 
}