1、矩形
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<html><head><meta charset="utf-8"><title></title></head><body><script>//嵌套循环:外层循环一次，内层循环一轮//矩形for (var j = 1; j <= 5; j++) {for (var i = 1; i <= 5; i++) {document.write("*")}document.write("<br>")}</script></body>
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1、 平行四边形
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<html><head><meta charset="utf-8"><title></title></head><body><script>//平行四边形for (var j = 1; j <= 5; j++) {for (var k = 5; k > j; k--) {document.write(" ")}for (var i = 1; i <= 5; i++) {document.write("*")}document.write("<br>")}</script></body>
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1、三角形
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<html><head><meta charset="utf-8"><title></title></head><body><script>//三角形for (var j = 1; j <= 5; j++) {//控制每一行缩进的空格for (var k = 5; k > j; k--) {document.write(" ");}//内层控制每一行的内容for (var i = 1; i <= 2 * j - 1; i++) {document.write("*");}document.write("<br>");}//正直角三角形for (var i = 1; i <= 5; i++) {for (var j = 1; j <= i; j++) {document.write("*");}document.write("<br>");}document.write("<br>");//倒直角三角形for (var i = 1; i <= 5; i++) {for (var j = 6; j > i; j--) {document.write("*");}document.write("<br>");}</script></body>
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