javascript - 我以前没见过的比较运算符

Question

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Answer 1

它是一个简单的三元运算符。

delay_start = (typeof delay_start_qs !== "undefined") 
                                ? !(delay_start_qs === "false") : true;

让我们打破它..

(typeof delay_start_qs !== "undefined")//如果 delay_start_qs 未定义

如果上述条件为真，则 delay_start = !(delay_start_qs === "false") ;

否则 delay_start = true;

同样可以写成for循环

if(typeof delay_start_qs !== "undefined") {
    delay_start = !(delay_start_qs === "false") ;
} else {
    delay_start = true;
}