Question

你好，我可以这样做：

$value = 0;
$test = $value === 0 ? 'it is zero!' : 'It is not zero.';
echo $test;

如何在不使用经典if - else if语句的情况下在php中的1行中完成此操作？

Answer 1

它仍然适用于javascript

value = 0;
var test = (value === 0 ? 'it is zero!' : 'It is not zero.');
console.log(test);

<强>输出

it is zero!

Answer 2

这应该有效：

var value = 0;
var test = (value === 0) ? 'It is zero' : 'It is not zero!';
console.log(test);

顺便说一下，它被称为三元运算符。 Many languages support them

Answer 3

几乎完全一样。

var value = 0;
var test = (value === 0) ? 'it is zero!' : 'it is not zero';
console.log(test);

输出：

"it is zero!"

Answer 4

除了你的$变成var。

之外没有这么大的区别

documentation

我总是喜欢内联三元。我个人觉得它更具可读性。

var test =(value===0)?'it is zero!':'It is not zero.';
console.log("test check==="+test)

DEMO：http://jsfiddle.net/jayeshjain24/efLYf/

Answer 5

Javascript也支持三元运算符。

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator

Answer 6

(value == 0)?alert('it is zero!'):alert('It is not zero.');

Answer 7

我可以在JS中做得更好1：

var value = 0;
console.log(value === 0 ? 'It is zero!' : 'it is not zero');

甚至更短：

console.log('it is ' + ((value = 0) === 0 ? '':'not ') + 'zero!');

Bang，你的3个PHP行的一行。请注意，如果value不存在，则将导致抛出错误（在严格模式下）或正在创建隐含的全局变量。
但是，如果变量value已经存在，那么所有变量都可以正常运行，并且行为与您期望的一样：

var value = 0;
console.log('it is ' + ((value = value || 0) === 0 ? '':'not ') + 'zero!');
//logs it is zero
value = 123;
console.log('it is ' + ((value = value || 0) === 0 ? '':'not ') + 'zero!');
//logs it is not zero

我使用IIFE进行了测试：

(function(value)
{//logs it is zero
    console.log('it is ' + ((value = value || 0) === 0 ? '':'not ') + 'zero!');
}());
    (function(value)
{//logs it is not zero
    console.log('it is ' + ((value = value || 0) === 0 ? '':'not ') + 'zero!');
}(123));
(function(value)
{//logs it is zero
    console.log('it is ' + ((value = value || 0) === 0 ? '':'not ') + 'zero!');
}(0));

当值未定义或伪造时，要避免来自loggin it is zero的代码：

(function(value)
{//coerce to numbner
    console.log('it is ' + (value === 0 || value === '0' ? '':'not ') + 'zero!');
}());

如果it is zero为value或'0'，则只会记录0。它不适用于false，undefined，null ...

等值

javascript内联if变量赋值如php

7 个答案: