算术运算符对数字(文字或变量)执行算术运算。
添加
减法
乘法
求幂 (ES2016)
分配
模数(余数)
增量
递减
典型的算术运算对两个数字进行运算。
这两个数字可以是文字:
let x = 100 + 50;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Arithmetic</h2>
<p>A typical arithmetic operation takes two numbers and produces a new number.</p>
<p id="demo"></p>
<script>
let x = 100 + 50;
document.getElementById("demo").innerHTML = x;
</script>
</body>
</html>
或变量:
let x = a + b;
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Arithmetic</h2>
<p>A typical arithmetic operation takes two numbers (or variables) and produces a new number.</p>
<p id="demo"></p>
<script>
let a = 100;
let b = 50;
let x = a + b;
document.getElementById("demo").innerHTML = x;
</script>
</body>
</html>
或表达式:
let x = (100 + 50) * a;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>Arithmetic Operations</h2>
<p>A typical arithmetic operation takes two numbers (or expressions) and produces a new number.</p>
<p id="demo"></p>
<script>
let a = 3;
let x = (100 + 50) * a;
document.getElementById("demo").innerHTML = x;
</script>
</body>
</html>
数字(在算术运算中)称为操作数。
运算(在两个操作数之间执行)由运算符定义。
Operand | Operator | Operand |
---|---|---|
100 | + | 50 |
加法运算符 (+
) 添加数字:
let x = 5;
let y = 2;
let z = x + y;
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The + Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
let y = 2;
let z = x + y;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>
减法运算符 (-
) 用于减去数字。
let x = 5;
let y = 2;
let z = x - y;
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The - Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
let y = 2;
let z = x - y;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>
乘法运算符 (*
) 将数字相乘。
let x = 5;
let y = 2;
let z = x * y;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The * Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
let y = 2;
let z = x * y;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>
除运算符 (/
) 用于除数。
let x = 5;
let y = 2;
let z = x / y;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The / Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
let y = 2;
let z = x / y;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>
取模运算符 (%
) 返回除法余数。
let x = 5;
let y = 2;
let z = x % y;
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The % Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
let y = 2;
let z = x % y;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>
在算术中,两个整数相除产生一个商 和余数。
在数学中,模运算的结果是算术除法的余数。
递增运算符 (++
) 递增数字。
let x = 5;
x++;
let z = x;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The ++ Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
x++;
let z = x;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>
递减运算符 (--
) 使数字递减。
let x = 5;
x--;
let z = x;
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The -- Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
x--;
let z = x;
document.getElementById("demo").innerHTML = z;
</script>
</body>
</html>
求幂运算符 (**
) 将第一个操作数计算为第二个操作数的幂。
let x = 5;
let z =
x ** 2;
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>The ** Operator</h2>
<p id="demo"></p>
<script>
let x = 5;
document.getElementById("demo").innerHTML = x ** 2;
</script>
</body>
</html>
x ** y 产生与 Math.pow(x,y)
相同的结果:
let x = 5;
let z =
Math.pow(x,2);
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>Math.pow()</h2>
<p id="demo"></p>
<script>
let x = 5;
document.getElementById("demo").innerHTML = Math.pow(x,2);
</script>
</body>
</html>
运算符优先级描述了运算执行的顺序 算术表达式。
let x = 100 + 50 * 3;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>Operator Precedence</h2>
<p>Multiplication has precedence over addition.</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 100 + 50 * 3;
</script>
</body>
</html>
上面例子的结果是和150 * 3一样,还是和100一样 + 150?
是先做加法还是先做乘法?
与传统的学校数学一样,首先进行乘法。
乘法 (*
) 和除法 (/
) 的优先级高于 加法 (+
) 和减法 (-
)。
并且(就像在学校数学中一样)可以通过使用来更改优先级 括号。
使用括号时,计算括号内的运算 第一的:
let x = (100 + 50) * 3;
自己尝试一下→
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>Operator Precedence</h2>
<p>Multiplication has precedence over addition.</p>
<p>But parenthesis has precedence over multiplication.</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = (100 + 50) * 3;
</script>
</body>
</html>
当许多操作具有相同的优先级时(例如加法和 减法或乘法和除法),它们从左到右计算 正确的:
let x = 100 + 50 - 3;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>Operator Precedence</h2>
<p>When many operations has the same precedence, they are computed from left to right.</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 100 + 50 - 3;
</script>
</body>
</html>
let x = 100 / 50 * 3;
自己尝试一下 →
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Arithmetic</h1>
<h2>Operator Precedence</h2>
<p>When many operations has the same precedence, they are computed from left to right.</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = 100 / 50 * 3;
</script>
</body>
</html>
有关运算符优先级值的完整列表,请访问:
JavaScript 运算符优先级值。