220 lines
4.5 KiB
Markdown
220 lines
4.5 KiB
Markdown
# 运算符相关
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1. 两个自定义变量进行相等对比，弹出运算结果。 （分别放两个按钮 第一个弹出==的比较结果 第二个弹出 ===的比较结果）
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2. 完成计算器的功能 输入两个数 输出计算结果 具体计算功能包含 加减乘除成方取余 每个计算方式分别放按钮 点击输出计算结果
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3. 用js 取模实现表格的隔行换色
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4. 求商取模应用于秒转时间 输入框单位为秒
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思路：不管输入框获取到的数字是多少，都执行除60取分钟，除600取小时，最后取模为秒数。通过parseInt取整数
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5. 判断是否为两位数
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6. 写出运算符优先级
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7. 计算年龄案例：输入生日输出年龄 并且判断是否能进入网吧
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8. 运算符的优先级
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9. 下面代码的执行结果为
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```
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var age = 29;
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var anotherAge = --age + 2;
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alert(age);
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alert(anotherAge);
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var time=1
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var newtime=time++
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console.log(time,newtime)
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```
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11. 下面代码的执行结果为
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```
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<script>
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var a =1;
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function test(){
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alert(a);
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var a = 2;
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alert(a);
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}
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test();
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alert(a);
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</script>
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```
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12. 下面代码的执行结果为
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```
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var x = 7;
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x += 8;
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console.log(x)
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var y=7
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y=+8;
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console.log(y)
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```
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13. 下面代码的执行结果为：
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```
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txt1 = "Hello ";
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txt1 += "Kitty!";
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console.log(txt1)
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console.log(x = 7 + 8;)
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console.log(y = "7" + 8;)
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console.log(z = "Hello" + 7;)
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```
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14. 已知 x=5 分别写出下列语句的打印结果
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x == 8
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x == 5
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x == "5"
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x === 5
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x === "5"
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x != 8
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x !== 5
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x !== "5"
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x !== 8
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x > 8
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x < 8
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x >= 8
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x <= 8
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15. 已知 x=6 y=3 分别写出下列语句的打印结果
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x < 10 && y > 1
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x == 5 || y == 5
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!(x == y)
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16. 已知现有fish="23"
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var cat = (fish < 18) ? "再来一筐锦鲤":"吃饱啦";
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最后的cat 打印结果为
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17. 写出下面的打印结果
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2 < 12
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2 < "12"
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2 < "John"
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2 > "John"
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2 == "John"
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"2" < "12"
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"2" > "12"
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"2" == "12"
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18. 写出下面的打印结果
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```
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txt1="What a very ";
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txt2="nice day";
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txt3=txt1+txt2;
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console.log(txt3)
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var x = 1;
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x = -x;
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alert( x );
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var x = 1, y = 3;
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alert( y - x );
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```
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19. 写出下面的打印结果
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```
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alert( 5 % 2 );
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alert( 8 % 3 );
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alert( 2 ** 2 );
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alert( 2 ** 3 );
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alert( 2 ** 4 );
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alert( 4 ** (1/2) );
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alert( 8 ** (1/3) );
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alert( '1' + 2 );
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alert( 2 + '1' );
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alert(2 + 2 + '1' );
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var x = 1;
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alert( +x );
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var y = -2;
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alert( +y );
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// 转化非数字
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alert( +true );
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alert( +"" );
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var apples = "2";
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var oranges = "3";
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alert( apples + oranges );
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alert( Number(apples) + Number(oranges) );
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```
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20. 运算符优先级
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21. 下面代码的执行结果为
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```
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let a = 1;
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let b = 2;
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let c = 3 - (a = b + 1);
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alert( a );
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alert( c );
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```
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```
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let a, b, c;
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a = b = c = 2 + 2;
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alert( a );
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alert( b );
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alert( c );
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let n = 2;
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n += 5;
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n *= 2;
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alert( n );
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let n = 2;
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n *= 3 + 5;
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alert( n );
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```
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22. 下面代码的打印结果为
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```
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alert( true || true ); // true
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alert( false || true ); // true
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alert( true || false ); // true
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alert( false || false ); // false
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```
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```
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alert( 1 || 0 );
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alert( null || 1 );
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alert( null || 0 || 1 );
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alert( undefined || null || 0 )
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var firstName = "";
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var lastName = "";
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var nickName = "SuperCoder";
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alert( firstName || lastName || nickName || "Anonymous");
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```
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23. 下面代码会执行嘛 为什么
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```
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true || alert("not printed");
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false || alert("printed");
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```
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24. 下面代码的执行结果
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```
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alert( 1 && 0 );
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alert( 1 && 5 );
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alert( null && 5 );
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alert( 0 && "no matter what" )
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alert( 1 && 2 && null && 3 )
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alert( 1 && 2 && 3 )
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alert( !!"non-empty string" );
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alert( !!null );
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alert( Boolean("non-empty string") );
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alert( Boolean(null) );
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alert( null || 2 || undefined );
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alert( alert(1) || 2 || alert(3) )
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alert( alert(1) && alert(2) );
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alert( null || 2 && 3 || 4 );
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```
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附加
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游戏开始时，显示12个图像的背面，用鼠标点击其中任意一张，即可显示图像的正面，如果点击了两张，则显示出两张图像的正面。如果点击过的两张图像是相同的图像，则将图像从界面中移除 |