JavaScript 中的“和”有什么区别？

我看到了 这个问题，我想知道同样的事情在 JavaScript 中。

在 JavaScript 中生成字符串时，如果使用字符’或字符”，应用程序的行为似乎也是一样的。那么这两个角色之间有什么区别呢？

我看到的用来构建字符串的唯一好处是我可以做这样的事情:

var toAppend = '<div id="myDiv1"></div>';

而不是:

var toAppend = "<div id=\"myDiv1\"></div>";

他们之间有什么重要的区别吗？

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最佳答案

They are equivalent for all intents and purposes. If you want to use either one inside a string, it is a good idea to use the other one to create the string, as you noted. Other than that, it's all the same.

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There's no difference. The reason for its existence is exactly what you mentioned

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I think there is another difference. If you do the following

var str1 = 'The \' character';
var str2 = 'The " character';
var str3 = "The ' character";
var str4 = "The \" character";
document.write(str1.replace("'", "%26"));
document.write(str2.replace('"', "%22"));
document.write(str3.replace("'", "%26"));
document.write(str4.replace('"', "%22"));

The document.write will fail for str1 and str4. That is the difference, but I don't know if there is a workaround to make them work.

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Although not technically a difference in Javascript, its worth noting that single quoted strings are not valid JSON, per se. I think that people automatically assume that since JSON is valid JS, that valid JS strings are also valid JSON, which isn't necessarily true.

E.g., {'key': 'Some "value"'} is not valid JSON, whereas {"key": "Some 'value'"} is.

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Good practice, according to Mozilla, is to use " " in HTML (where ' ' cannot be used) while reserving ' ' in Javascript (where both " " and ' ' can be use indifferently)...

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Try this:

console.log("mama+"mama"")


Output : Uncaught SyntaxError: missing )
after argument list

Now try:

console.log('mama+"mama"')


Output :  mama+"mama"

They are equivalent! but sometimes you want to use "" inside a string, and that why we have '

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WARNING!!!!

There is a difference. When adding to arrays, you have to use one or the other. The array gets confused when you use two different types of quotes.

Example:

//WILL NOT WORK
var array = ["apple","orange","banana"];


array.push('pear');


//WILL WORK
var array = ["apple","orange","banana"];


array.push("pear");
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As written above, there is no difference but for situation you need to use "/' inside a string.

I think a better practice for situation you need to concatenate strings with variables is using a template strings: Price: ${price}, Amount: ${amount}. Total: ${price*amount}

That's way you can add " and ', and concatenate variables.

Much easier to read, much easier to write.


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