var j = 1;
for (var i = 2; i < 101; i++) {
console.log(j + '+' + i + '=' + (j += i));
}
//运行结果
/*
1+2=3
3+3=6
6+4=10
10+5=15
15+6=21
21+7=28
28+8=36
36+9=45
45+10=55
55+11=66
66+12=78
78+13=91
91+14=105
105+15=120
120+16=136
136+17=153
153+18=171
171+19=190
190+20=210
210+21=231
231+22=253
253+23=276
276+24=300
300+25=325
325+26=351
351+27=378
378+28=406
406+29=435
435+30=465
465+31=496
496+32=528
528+33=561
561+34=595
595+35=630
630+36=666
666+37=703
703+38=741
741+39=780
780+40=820
820+41=861
861+42=903
903+43=946
946+44=990
990+45=1035
1035+46=1081
1081+47=1128
1128+48=1176
1176+49=1225
1225+50=1275
1275+51=1326
1326+52=1378
1378+53=1431
1431+54=1485
1485+55=1540
1540+56=1596
1596+57=1653
1653+58=1711
1711+59=1770
1770+60=1830
1830+61=1891
1891+62=1953
1953+63=2016
2016+64=2080
2080+65=2145
2145+66=2211
2211+67=2278
2278+68=2346
2346+69=2415
2415+70=2485
2485+71=2556
2556+72=2628
2628+73=2701
2701+74=2775
2775+75=2850
2850+76=2926
2926+77=3003
3003+78=3081
3081+79=3160
3160+80=3240
3240+81=3321
3321+82=3403
3403+83=3486
3486+84=3570
3570+85=3655
3655+86=3741
3741+87=3828
3828+88=3916
3916+89=4005
4005+90=4095
4095+91=4186
4186+92=4278
4278+93=4371
4371+94=4465
4465+95=4560
4560+96=4656
4656+97=4753
4753+98=4851
4851+99=4950
4950+100=5050
*/