for循环九九乘法表for (let i 1; i 9; i) {for (let j 1; j i; j) {document.write(span${j}*${i}${j * i}/span)}document.write(br)}while循环let i 1while (i 10) {document.write(${i}br)i 不然为死循环}do while循环let i 11do {console.log(i)i} while (i 10)注do while循环中的do不看条件至少执行一次然后再做while的条件判断for (let i 1; i 100; i) {if (i 50) {break 跳出循环continue 跳出本次循环直接开始下一次循环}console.log(i)}数组1、[元素1,元素2,……] let arr1 [zhangsan, 1, 2, true]数组下标从0开始通过数组下标数组名[下标] console.log(arr1[0])可通过数组下标重新对对应的数组元素进行赋值arr1[1] 666console.log(arr1)2、判断数据类型console.log(typeof (arr1))3、判断是否是数组类型Array.isArray(arr1)arr1 instanceof (Array)console.log(arr1 instanceof (Array))4、其他声明方式let arr2 new Array()let arr2 new Array(1, 2, 3, 4, zhangsan)5、二维数组let arr3 [[zhangsan, 21], [lisi, 22]]console.log(arr3[0][1]) 取出21数组的遍历let arr [1, 2, 3, 4, 5, zhangsan]console.log(arr.length) 返回数组中元素的个数for (let i 0; i arr.length - 1; i) {console.log(arr[i])}循环加强:for in for offor (let i in arr) {console.log(arr[i])}for (let i of arr) {console.log(i) 直接打印数组中的数据}数组的方法数组名.属性名/数组名.方法名()in运算符查键名let arr1 [aaa, 1, 2]console.log(4 in arr1) false1、unshift(lisi)向数组的开头添加一个或多个元素arr1.unshift(lisi, zhangfei)console.log(arr1)2、push()向数组的最后添加一个或多个元素arr1.push(wangmazi)console.log(arr1)3、删除shift()删除并返回数组的第一个元素let a arr1.shift()console.log(a)arr1.shift()console.log(arr1)4、pop()删除并返回数组的最后一个元素let a arr1.pop()console.log(a)arr1.pop()console.log(arr1)5、splice(删除元素的起始位置删除几个元素)!DOCTYPE htmlhtml langenheadmeta charsetUTF-8meta nameviewport contentwidthdevice-width, initial-scale1.0titleDocument/title/headbodyscriptwindow.onloadfunction(){function times(){let datenewDate()let timedocument.getElementById(time)let yeardate.getFullYear()let monthdate.getMonth()1let daydate.getDate()let hourdate.getHours()let minutedate.getMinute()let seconddate.getSecond()let daysdate.getDay()let dayssswitch(days) {case 1:dayss一;breakcase 2:dayss二;breakcase 3:dayss三;breakcase 4:dayss四;breakcase 5:dayss五;breakcase 6:dayss六;breakcase 7:dayss七;break}time.innerTextyear年month月day日hour:minute:second星期dayss}times()setInterval(times,1000)}/script/body/html 
长河君 · 2026/8/22 12:13:56 · 阅读 1.2k css练习
for循环九九乘法表for (let i 1; i 9; i) {for (let j 1; j i; j) {document.write(span${j}*${i}${j * i}/span)}document.write(br)}while循环let i 1while (i 10) {document.write(${i}br)i 不然为死循环}do while循环let i 11do {console.log(i)i} while (i 10)注do while循环中的do不看条件至少执行一次然后再做while的条件判断for (let i 1; i 100; i) {if (i 50) {break 跳出循环continue 跳出本次循环直接开始下一次循环}console.log(i)}数组1、[元素1,元素2,……] let arr1 [zhangsan, 1, 2, true]数组下标从0开始通过数组下标数组名[下标] console.log(arr1[0])可通过数组下标重新对对应的数组元素进行赋值arr1[1] 666console.log(arr1)2、判断数据类型console.log(typeof (arr1))3、判断是否是数组类型Array.isArray(arr1)arr1 instanceof (Array)console.log(arr1 instanceof (Array))4、其他声明方式let arr2 new Array()let arr2 new Array(1, 2, 3, 4, zhangsan)5、二维数组let arr3 [[zhangsan, 21], [lisi, 22]]console.log(arr3[0][1]) 取出21数组的遍历let arr [1, 2, 3, 4, 5, zhangsan]console.log(arr.length) 返回数组中元素的个数for (let i 0; i arr.length - 1; i) {console.log(arr[i])}循环加强:for in for offor (let i in arr) {console.log(arr[i])}for (let i of arr) {console.log(i) 直接打印数组中的数据}数组的方法数组名.属性名/数组名.方法名()in运算符查键名let arr1 [aaa, 1, 2]console.log(4 in arr1) false1、unshift(lisi)向数组的开头添加一个或多个元素arr1.unshift(lisi, zhangfei)console.log(arr1)2、push()向数组的最后添加一个或多个元素arr1.push(wangmazi)console.log(arr1)3、删除shift()删除并返回数组的第一个元素let a arr1.shift()console.log(a)arr1.shift()console.log(arr1)4、pop()删除并返回数组的最后一个元素let a arr1.pop()console.log(a)arr1.pop()console.log(arr1)5、splice(删除元素的起始位置删除几个元素)!DOCTYPE htmlhtml langenheadmeta charsetUTF-8meta nameviewport contentwidthdevice-width, initial-scale1.0titleDocument/title/headbodyscriptwindow.onloadfunction(){function times(){let datenewDate()let timedocument.getElementById(time)let yeardate.getFullYear()let monthdate.getMonth()1let daydate.getDate()let hourdate.getHours()let minutedate.getMinute()let seconddate.getSecond()let daysdate.getDay()let dayssswitch(days) {case 1:dayss一;breakcase 2:dayss二;breakcase 3:dayss三;breakcase 4:dayss四;breakcase 5:dayss五;breakcase 6:dayss六;breakcase 7:dayss七;break}time.innerTextyear年month月day日hour:minute:second星期dayss}times()setInterval(times,1000)}/script/body/html