Javascript 中的 += 是什么？
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What is += in Javascript?
提问by HappyHands31
For example, in the while loop:
例如，在while循环中：
while (i < 10) {
text += "The number is " + i;
i++;
}
What does it do? Thanks.
它有什么作用？谢谢。
回答by Felipe Oriani
It is the addition assignmentoperator (+=) to add a value to a variable.
它是addition assignment操作者（+=）到一个值添加到一个变量。
Depending of the current type of the defined value on a variable, it will read the current value add/concat another value into it and define on the same variable.
根据变量上定义值的当前类型，它将读取当前值添加/连接另一个值并在同一变量上定义。
For a string, you concat the current value with another value
对于 a string，您将当前值与另一个值连接起来
let name = "User";
name += "Name"; // name = "UserName";
name += " is ok"; // name = "UserName is ok";
It is the same:
这是相同的：
var name = "User";
name = name + "Name"; // name = "UserName";
name = name + " is ok"; // name = "UserName is ok";
For numbers, it will sum the value:
对于数字，它将对值求和：
let n = 3;
n += 2; // n = 5
n += 3; // n = 8
In Javascript, we also have the following expressions:
在 Javascript 中，我们还有以下表达式：
-=- Subtraction assignment;/=- Division assignment;*=- Multiplication assignment;%=- Modulus (Division Remainder) assignment.
-=- 减法赋值；/=- 部门分配；*=- 乘法赋值；%=- 模数（除法余数）分配。
回答by slomek
text += "The number is " + i;
is equivalent to
相当于
text = text + "The number is " + i;
