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<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>while循环</title>
</head><body><script>// // 1.变量的起始值// let i = 1// // 2.终止条件// while (i <= 3) {// document.writeln('循环三次 <br>')// i++// }// 1.变量的起始值let j = +prompt('请输入需要循环的次数')let i = 1// 2.终止条件while (i <= j) {document.writeln('循环三次 <br>')i++}</script>
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练习：
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<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>循环大练习</title>
</head><body><script>// 1.页面输出0~100// let i = 1// while (i <= 100) {// document.write(`这是输出的第${i}个数 <br>`)// i++// }// 2.计算1加到100的总和并输出// let i = 1// let sum = 0// while (i <= 100) {// sum = sum + i// i++// }// document.write(sum)//5050// 3.计算1到100之间的所有偶数和并输出let i = 1let sum = 0while (i <= 100) {// 筛选偶数if (i % 2 === 0) {sum += i}i++}document.write(sum)</script>
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