一个非常基本的程序，没什么看头，基本就是一大堆定理算出来，写的在里是发现CSS3出来后，算角度的需求越来越多，每次算还要用到笔纸，与是乎总结下来搞这样一个小工具，由于需求一般都是直角的，所以这里只算直角，根据两边长度求角度。 函数中的sins是拷贝的一份正弦表，我把它倒了方向写成了一个对象，没什么看头，可以看源码（一个很长的json）,这里的思路是取这个正弦值最附近的一位在sins中有key的，就返回它的角度。 ~~~ var sins={ 0017:0.1,0035:0.2,0052:0.3,0070:0.4,0087:0.5,0105:0.6,0122:0.7,0140:0.8,0157:0.9,0175:1.0,0192:1.1,0209:1.2,0227:1.3,0244:1.4,0262:1.5,0279:1.6,0297:1.7,0314:1.8,0332:1.9,0349:2.0,0366:2.1,0384:2.2,0401:2.3,0419:2.4,0436:2.5,0454:2.6,0471:2.7,0488:2.8,0506:2.9,0523:3.0,0541:3.1,0558:3.2,0576:3.3,0593:3.4,0610:3.5,0628:3.6,0645:3.7,0663:3.8,0680:3.9,0698:4.0,0715:4.1,0732:4.2,0750:4.3,0767:4.4,0785:4.5,0802:4.6,0819:4.7,0837:4.8,0854:4.9,0872:5.0,0889:5.1,0906:5.2,0924:5.3,0941:5.4,0958:5.5,0976:5.6,0993:5.7,1011:5.8,1028:5.9,1045:6.0,1063:6.1,1080:6.2,1097:6.3,1115:6.4,1132:6.5,1149:6.6,1167:6.7,1184:6.8,1201:6.9,1219:7.0,1236:7.1,1253:7.2,1271:7.3,1288:7.4,1305:7.5,1323:7.6,1340:7.7,1357:7.8,1374:7.9,1392:8.0,1409:8.1,1426:8.2,1444:8.3,1461:8.4,1478:8.5,1495:8.6,1513:8.7,1530:8.8,1547:8.9,1564:9.0,1582:9.1,1599:9.2,1616:9.3,1633:9.4,1650:9.5,1668:9.6,1685:9.7,1702:9.8,1719:9.9,1736:10.0,1754:10.1,1771:10.2,1788:10.3,1805:10.4,1822:10.5,1840:10.6,1857:10.7,1874:10.8,1891:10.9,1908:11.0,1925:11.1,1942:11.2,1959:11.3,1977:11.4,1994:11.5,2011:11.6,2028:11.7,2045:11.8,2062:11.9,2079:12.0,2096:12.1,2113:12.2,2130:12.3,2147:12.4,2164:12.5,2181:12.6,2198:12.7,2215:12.8,2233:12.9,2250:13.0,2267:13.1,2284:13.2,2300:13.3,2317:13.4,2334:13.5,2351:13.6,2368:13.7,2385:13.8,2402:13.9,2419:14.0,2436:14.1,2453:14.2,2470:14.3,2487:14.4,2504:14.5,2521:14.6,2538:14.7,2554:14.8,2571:14.9,2588:15.0,2605:15.1,2622:15.2,2639:15.3,2656:15.4,2672:15.5,2689:15.6,2706:15.7,2723:15.8,2740:15.9,2756:16.0,2773:16.1,2790:16.2,2807:16.3,2823:16.4,2840:16.5,2857:16.6,2874:16.7,2890:16.8,2907:16.9,2924:17.0,2940:17.1,2957:17.2,2974:17.3,2990:17.4,3007:17.5,3024:17.6,3040:17.7,3057:17.8,3074:17.9,3090:18.0,3107:18.1,3123:18.2,3140:18.3,3156:18.4,3173:18.5,3190:18.6,3206:18.7,3223:18.8,3239:18.9,3256:19.0,3272:19.1,3289:19.2,3305:19.3,3322:19.4,3338:19.5,3355:19.6,3371:19.7,3387:19.8,3404:19.9,3420:20.0,3437:20.1,3453:20.2,3469:20.3,3486:20.4,3502:20.5,3518:20.6,3535:20.7,3551:20.8,3567:20.9,3584:21.0,3600:21.1,3616:21.2,3633:21.3,3649:21.4,3665:21.5,3681:21.6,3697:21.7,3714:21.8,3730:21.9,3746:22.0,3762:22.1,3778:22.2,3795:22.3,3811:22.4,3827:22.5,3843:22.6,3859:22.7,3875:22.8,3891:22.9,3907:23.0,3923:23.1,3939:23.2,3955:23.3,3971:23.4,3987:23.5,4003:23.6,4019:23.7,4035:23.8,4051:23.9,4067:24.0,4083:24.1,4099:24.2,4115:24.3,4131:24.4,4147:24.5,4163:24.6,4179:24.7,4195:24.8,4210:24.9,4226:25.0,4242:25.1,4258:25.2,4274:25.3,4289:25.4,4305:25.5,4321:25.6,4337:25.7,4352:25.8,4368:25.9,4384:26.0,4399:26.1,4415:26.2,4431:26.3,4446:26.4,4462:26.5,4478:26.6,4493:26.7,4509:26.8,4524:26.9,4540:27.0,4555:27.1,4571:27.2,4586:27.3,4602:27.4,4617:27.5,4633:27.6,4648:27.7,4664:27.8,4679:27.9,4695:28.0,4710:28.1,4726:28.2,4741:28.3,4756:28.4,4772:28.5,4787:28.6,4802:28.7,4818:28.8,4833:28.9,4848:29.0,4863:29.1,4879:29.2,4894:29.3,4909:29.4,4924:29.5,4939:29.6,4955:29.7,4970:29.8,4985:29.9,5000:30.0,5015:30.1,5030:30.2,5045:30.3,5060:30.4,5075:30.5,5090:30.6,5105:30.7,5120:30.8,5135:30.9,5150:31.0,5165:31.1,5180:31.2,5195:31.3,5210:31.4,5225:31.5,5240:31.6,5255:31.7,5270:31.8,5284:31.9,5299:32.0,5314:32.1,5329:32.2,5344:32.3,5358:32.4,5373:32.5,5388:32.6,5402:32.7,5417:32.8,5432:32.9,5446:33.0,5461:33.1,5476:33.2,5490:33.3,5505:33.4,5519:33.5,5534:33.6,5548:33.7,5563:33.8,5577:33.9,5592:34.0,5606:34.1,5621:34.2,5635:34.3,5650:34.4,5664:34.5,5678:34.6,5693:34.7,5707:34.8,5721:34.9,5736:35.0,5750:35.1,5764:35.2,5779:35.3,5793:35.4,5807:35.5,5821:35.6,5835:35.7,5850:35.8,5864:35.9,5878:36.0,5892:36.1,5906:36.2,5920:36.3,5934:36.4,5948:36.5,5962:36.6,5976:36.7,5990:36.8,6004:36.9,6018:37.0,6032:37.1,6046:37.2,6060:37.3,6074:37.4,6088:37.5,6101:37.6,6115:37.7,6129:37.8,6143:37.9,6157:38.0,6170:38.1,6184:38.2,6198:38.3,6211:38.4,6225:38.5,6239:38.6,6252:38.7,6266:38.8,6280:38.9,6293:39.0,6307:39.1,6320:39.2,6334:39.3,6347:39.4,6361:39.5,6374:39.6,6388:39.7,6401:39.8,6414:39.9,6428:40.0,6441:40.1,6455:40.2,6468:40.3,6481:40.4,6494:40.5,6508:40.6,6521:40.7,6534:40.8,6547:40.9,6561:41.0,6574:41.1,6587:41.2,6600:41.3,6613:41.4,6626:41.5,6639:41.6,6652:41.7,6665:41.8,6678:41.9,6691:42.0,6704:42.1,6717:42.2,6730:42.3,6743:42.4,6756:42.5,6769:42.6,6782:42.7,6794:42.8,6807:42.9,6820:43.0,6833:43.1,6845:43.2,6858:43.3,6871:43.4,6884:43.5,6896:43.6,6909:43.7,6921:43.8,6934:43.9,6947:44.0,6959:44.1,6972:44.2,6984:44.3,6997:44.4,7009:44.5,7022:44.6,7034:44.7,7046:44.8,7059:44.9,7071:45.0,7083:45.1,7096:45.2,7108:45.3,7120:45.4,7133:45.5,7145:45.6,7157:45.7,7169:45.8,7181:45.9,7193:46.0,7206:46.1,7218:46.2,7230:46.3,7242:46.4,7254:46.5,7266:46.6,7278:46.7,7290:46.8,7302:46.9,7314:47.0,7325:47.1,7337:47.2,7349:47.3,7361:47.4,7373:47.5,7385:47.6,7396:47.7,7408:47.8,7420:47.9,7431:48.0,7443:48.1,7455:48.2,7466:48.3,7478:48.4,7490:48.5,7501:48.6,7513:48.7,7524:48.8,7536:48.9,7547:49.0,7559:49.1,7570:49.2,7581:49.3,7593:49.4,7604:49.5,7615:49.6,7627:49.7,7638:49.8,7649:49.9,7660:50.0,7672:50.1,7683:50.2,7694:50.3,7705:50.4,7716:50.5,7727:50.6,7738:50.7,7749:50.8,7760:50.9,7771:51.0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}; function toMath(x,y){ var z=Math.sqrt(x*x+y*y); var skey=Math.floor(x/z*10000); if(!sins.hasOwnProperty(skey)){ for(var i=1;i<=100;i++){ var akey = skey - i; if(sins.hasOwnProperty(akey)){ skey = akey; break; } var bkey = skey + i; if(sins.hasOwnProperty(bkey)){ skey = bkey; break; } } } return {'x':x,'y':y,'z':z,'a':sins[skey],'b':90-sins[skey]}; } console.log(toMath(50,50)) ~~~