问题描述
我不知道是否可能重复.测试我的代码，有时我错了，因为我在条件中输入了 = 而不是 == 或 ===
I don't know if it's possible duplicate. Testing my code, sometimes I was wrong with because I put = and not == or === in if conditions:
考虑以下代码:
var a = 0;
if(a = 1) console.log('true');
我不知道为什么这不是错误，为什么返回true条件(a = 1)我想这是将 1 分配给 a 变量，但是为什么它的计算结果为true并且没有错误?
I don't know why this is not an error and why returns true the condition (a = 1)I guess that what it does is assign 1 to the a variable, but why this evaluates to true and there's no error?
推荐答案
您要将a设置为1，然后检查结果的真实性.JavaScript中的非零数字是真实的，因此您得到的是所见即所得.
you're setting a to 1 and then checking the truthiness of the result. Non-zero numbers in JavaScript are true, so you get what you see.
就像数学一样，事物从左到右进行评估，首先是括号.
Like in math, things are evaluated left-to-right, with parens going first.
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