Regular Expressions!

For my test input of 5310 chars it still crashes.
After quite a while i get this error message:

Uncaught Error: Unknown escape character 117 in RegEx
 at line 1 col 184
...{return a.charCodeAt(0)%10})
                              ^
in function "dec" called from line 2 col 229
...)%10})};console.log(dec(img).length);
                              ^
>

Here is the full example code to reproduce:

let img = '720/Ç66/D65/gf64/wB64/ÆAH63/+2Af63/g2A63/ÂÇAD63/PÄwP62/wPjg62/+Q/PD62/nDÆ+PÆ60/Æ+PÃÂ/j60/l2/vzÂP59/Æj/+/PAf59/kv/ÅÇwB59/Æw2/P¾AH59/lv/Æ/Bwf58/+C2/zÂfh59/wJ2/OF/H58/+Uz/ÃzÁ+f58/yfn/m/fÂ59/A/v+Gd/j58/ÃD/fÂÃÁ/P58/kÁ2/G2fÆ58/+3/ÇÅ2/Ã58/z3/k3/n58/N2/Æz2/+f57/ÆD2/h/Ç/Ã58/yf/Æj3/n58/J2/n2/f+P57/Æ2/ÆP/µ/Â58/Ã2/Àf/f/j58/n/+M2/f+P58/P/ÅÃÆL/Âf57/Æ2/OTÄH/h58/Ã/ÇcnÆ/+X58/zžÆPÅ/Ãf58/nzTÂfv/l57/A2Ph/x3/H56/wACPk/jf/Æf56/P/AOT/l2/x56/ÄP/ÂM2/f2/H56/ef/ÆD/Æ/f+f55/Å+f/jÁ/ÃÇ/Â56/v2/ÆÇP2ÁÅ/j55/Æv2/BÄ/vPn+P55/wP/Ç2x2+/PÃ55/+b2/r/zÃ/+/n55/Å2/ÇH/2nÁÇÄf55/v2/kf/O2fÅp55/+j/ÆÅ/+Z+/ÀH55/ÄP/z2/ÆnÇ/IfÂf53/oH/f2/ÂPz+BÆAP52/+H/Ã3/ÂfnÂPn/P52/z2/v3/Â/OQÆgGf52/P/+4/w+YDg/B52/Æj/Å4/xÆAMf/P52/ÄP/v4/wIAn/+f52/v/Æ5/w2Af/Ã52/+2/r/ÂA2/gAH2/z52/ÃPÇvYHÆf/gA3/P52/k+W+x2/D+AD56/PÆb/Â2/g2Af55/Æ/zv/+f2/AB56/Ã+u5/+AP56/zÄÅ3/v/wA57/vlP3/P+AD56/+fE3/+PwEf56/Æ+D3/+GAx57/ÃÆP4/AHP57/zÃ5/ÃÆ24/Af32/nj4/+fÁ23/gAD32/nP2/v/j/f22/Æf+D32/M/Á2+I25/n2/D31/+TÄÁÅÂP24/Ç2/ÀH31/ÆPÂ2/j25/n/vbH31/Âfn/w23/f/O/+AvP31/ÃÆ/ÆP22/ÂfgT2/Â+f31/zÁ+H23/sÆcP2/zÂ32/nfB23/+ÂJw3/vL32/IB24/zxnB2/ÆÇn32/g24/fvÅZn2/ÁnP+H54/Â+PlnO/+Qc/yP54/ÁÆfGcz/ÂMb2+f55/xÆZÃf/HÂHÅÃ56/HÃPk/Æ2/f/n55/Ævk/T/n/2Ç+f55/m/HÆDÆ2/zÁÃ55/gfÆ/yfn2/PfnÇ31/v21/ÂA/z/DÆ2/ÆÃ+Pj52/+BÂ/PÆfn2/zPÆeP52/2jÃ+fxÆ3/J/Æf52/ÆfHzÃ/PÁ2/ÆP55/n+fÁjÂ+f2/z/z2/Á50/Æ/Æ/OHnÃ2/+f/f2/f50/Á/z+dc/P2/h/Ç/PÇ50/+f/vǾnÆ/+AP2/Ç8/Âf10/gf30/Ã/+fzo/j+AF11/+EP7/+3A31/v/Ã/OH+PgBn11/n+P6/4AZ30/Æ2/z+ÆfÂÆDÆ5/P5/Ã/+P5/ADg2Az30/z2/PÃx/jgPH4/Æ5/Æf/+f4/xP2/wBH30/P/+fzT+MBx5/Á5/H2/Æ4/Æb3/hCf29/Ç2/Â/FnÂQcf/ÆA7/z/wDÇ4/nf3/iL30/Á/ÁzÆGfhBn2/2AQB4/Æ/ÂPBz3/ÆÅ3/+EP30/f+PjwIÆAE2/w/w2AR2/Æf+P/xn3/Pf3/ÆY30/Â/Â/2AzgAn/+H/Â/gD/ÆP/x2/xP2/2Ã4/Âj30/j3/ABMACf/h2/w4AH/+f2/wf/+OP4/iP29/+H3/AQ2AZ/wP2/gH/gHÃ/n3/w2/Bz4/mI30/ÃP3/BgH3AD/f/P4/nÆ4/wGAÆf4/cD30/if2/ÆHAC3A/Ã/+f4/fn4/ÂAMH5/ÂP29/+M3/wO2AOAD/v/Ã5/Æ6/gP6/g30/Âd3/gcAQYAH3/Á5/n14/D30/gÃ2/+AQBAgYP3/f4/Æ15/H29/+Rx2/Æ2AECIÂ3/Æ5/Á14/+BÂ28/Çjx2/Æ2AwAjz3/z4/+15/ÆD29/zDx2/+CGAGHP3/v4/Á15/Â3/f26/OBzh2/HwA2c3/+f3/+f15/Â2/Å26/Æ+2AR/2AEDwz3/Â4/Å16/Â29/Å+Hgw3AGHDn3/j4/f16/ÂD28/n2/xÃgDCYcOf2/+f3/Ã47/f2/BÂAIJhÂZ3/Ã4/P48/vÂ2ABhmHh4/n3/Ã47/PÆ/k2AEAQPD3/Æf3/P47/Ã2/ÂEAY2B¾H3/x3/Ã48/x/+2AzgECIP3/T2/Âf48/w/gI+fCAMwf2/ÇP2/j49/gAZPj+MA/gf2/kf/Âf49/ÆfJw/ÆwD/gP/+E/wH51/Ãsf/ÃgH/AP/w2AD52/EH2/nAf/AP/2AD52/Æx2/+eA2/gHwAH53/jP2/2ÆD2/g2A54/+c3/xÂP2/2Af54/Ãz3/HÂf2/AD55/OP2/ÆPÂ2/+Af54/ÆÂ3/yfx2/ÆD55/zJ3/J/n2/Âf55/Iz2/Çn+D2/j55/ÆDn/HnfÆH/+f55/wfDwcÇ/wf/z56/B/AMHÁ/D/+P55/ÆH2/Ç/fÆn/j56/wf3/Ç/zDwf56/B4/Á/OAH56/ÆH3/+fÆ+D57/Âf3/Ã/z59/h4/n/P58/+H3/+fÆ59/ÆfÃ2/Ã/z59/w/Á2/n+f59/g3/+PÃ59/+Q+ADÂ/P59/Æw2ABhÆ60/zÂf+AXn60/P3/BI60/+f3/AH60/Ã3/+B61/x66/h66/D66/D66/H65/+f65/Æ6/x59/z5/ÆD59/v5/gH58/+f4/+cP58/Ã5/zÂ59/Á5/Pj59/f4/ÃHP58/Ç5/gM59/Á4/ÆAT59/P4/hwP58/+4/Æfg59/Ã4/j/D59/Á3/ÆfÆf59/v3/n/Ã59/+f2/Â2/j59/+f2/P/+P59/Æf/x2/Æ60/ÆfÆf2/z60/ÆCH3/P65/+f65/Ç66/Å66/j66/h66/ÃÂf65/h644/869A5/Æ60AH6/g59Af6/w58AB7/Â58AH7/w58Af7/w57AB8/w2ADwABÂABÂAH/+AHw3AfP4/gH3/hÂ2ABÂAP/ÆAD3/ÂB4/Æ4AH8/g2AP2AHgAHgD2/+APg2ADÂ4/+B3/+Hg2AHgD2/ÆAP3/ÂH4/w4Af8/3AÆ2Ae2AeAf2/+A+3APj4/ÂP3/Âe3AeA3/ÆA4/wf4/4AB6/Ã/+2ADwABÂABÂD3/ÆBÆ2ABÆP4/h4/hÂ2ABÂH3/ÂD4/h4/Æ4AH6/H/Æ2AP2AHgAHgf3/ÂHw2AHw4/+H3/+Hg2AHg4/wP4/H4/w4Af5/Âf/Â2AÆ2Ae2AeB/wD/gPg2A+DÂ4Afw3Ae3AeD/gH/AÆ2AfÆf8AB6/B2/wADwABÂABÂPÂAB/A+2ADÂP4ABÂ3ABÂ2ABÂfwAD+Dw2AHxÂ8AH5/ÂH2/2AP2AHgAHg/2ABÆBÆ2AfAÆ4AHg3AHg2AHh+2ADÂP3APHg8Af5/Af/+2AÆ2Ae2AeDÂ2AHwDwABÆDw4Ae4Ae3AeHw2APgÆ3AÆe8AB5/ÂB2/ÆADwABÂABÂP3APAPgAPgPg3ABÆ3ABÆ2ABÂe3AeDw2ADxÆ8AH5/AH2/wAP2AHgAHgÆ3AÆAf2A+A4/AH3/wH4/hÂ2ABÂP3APH3/Â5Af4/ÆAf2/gAÆ2Ae2AeDw2ADwBÆAHwD3/ÆAf3/wf3/+Hg2AHgÆ3AÆf3/g4AB5/gB2/+ADwABÂABÂP3APADÂAfAP3/wB4/h4/Âe3AeDw2ADx3/+5AH4/+AH2/ÆAP2AHgAHgÆ3AÆAPgDÂA4/AB3/+H4/hÂ2ABÂP3AfH3/Â5AfAHwHÆAeD/wAÆ2Ae2AeDw2ADwAfAPAD3/ÆAB3/Æf3/+Hg2AHg4/Æf3/g4ABÆAfAfgBwH/ADwABÂABÂP4/ABÆBÆAP8APxÂ2ABÂf3/+D4/xÆ8AHwBÆB+AHAf+AP2AHgAHg4/ÆADÂHgAÆ8AfHg2AHh4/ÂP3/+Hg8AfAHgDÂBÆA/ÂAÆ2Ae2AeD4/wAPg+ADw8AÆe3AeH4/g4/we8ABÆAOAPAPgD/gDwABÂABÂP4/2AfDwAP8ADxÂ2ABÂf3/+D3/+BÂ8AHÂAÂAÆA+AH/AP2AHgAHg4/ÆABÆf2AÆ8APHg2AHh4/ÂP2/fAHg8AfgBABgDwAfÆAÆ2Ae2AeDw2AHwADÅÂADw8AÆe3AeHw2AHgÆPÆ2Ae8AB+AEAGAf2A/wDwABÂABÂP3AP2APvgAP8ADxÂ2ABÂe3AeDwfÂABÂ8AHÆAQAQBÂAD/AP2AHgAHgÆ3AÆ2AfÆ2AÆ8APHg2AHhÂ2ABÂPAfÂAHg8Afw4ADgAHÆA+2Ae2A+Dw2ADwAB/wADw7ABÆe3AeHg2AHgÆA/wAe8AB/5AM2AfwD/ADÂA/ÂP3AP2AD+2APg6AB/xÂ2ABÂe3AeDwA/wBÆ8AH+5AQ2A/AP6/gÆ3AÆ2APÂ2A4/+P4/Hg2AHhÂ2ABÂPAB/gH4/w4AfÂ4AB2ADÆA6/+Dw2ADw2Af2AD4/Âf3/Âe3AeHg2AHgÆAB/Af4/4AB/g7AHwB6/wP3AP2ABÆ2AP4/h4/BÂ2ABÂe3AeDwAD/B4/Æ4AD/6AEAfAB5/+AÆ3AÆ2ADg2A4/+H3/ÂHg2AHhÂ2ABÂP2AH+H4/w4APÆAC4AYAÆ2A5/ADw2ADw2AM2AD4/Âf2/ÆAe3AeHg2AHgÆ2AH+f4/5A/wAM3ADgDw55AD/gAw3APAP56AP+AHAB2AÆAÆ56A/ÂAeAMAHgDw55AB/wBÂAÂAeAf56AH/APgDgDÂBÆ56AfÆA/AeAPAPw56A/ÂDÆBÆBÆA/2AB30Ag7AQ14AD/gfwPwHgHÆ2AE29AC7AB15AH+B/g2/ÂAfw2AQ29AI7AE15Af6/gD/2AB30Ag7AQ15A6/+AfÆAÆEeAHiEwPg2A+IgABA+AeAfARÂOAHwACPADxCYHx3AIHxAYPg5AD6/ÂA/wGYWMBhoU2D2AGMiAgE2ODMHGBIzGBhgALGAw¾KBxkQEAhxkeBhg5AH6/gD/AQBgYMBhgYC2AgOIDA2g2IAwEHBwIMB2AwMGB2wMBxAY2EBxwID6AP5/+AfÆBAGAhg2GBAEAEAYQcCEAQgCAIYDA2gCADAQwDCAgDCDgQgDGBgE6A6/ÂD/wEAQCEAIQMAQAwBhB2YQBiAYAhgIDGAIAIBCAEIGAMILCGAMYEAI5AB6/gf/AMBAIQAhA2/gCA2CEhD/+GBADEAgMf/gAgEIAQgQAQxkIQARgf/g5AD5/+D/ÆAYEAhACED3AIA2Ij2M2AMEAMQCAxg2ACAQgBCBA2BERhABGB8AH5/Âf/wAYQCEAIQI3AgAgyE2g2AMQAxAIDE3AIBCAEIEA2EQkEAEYE8AP5/j2/2AhAIQAhAw2ADAGBQSB3ARACEAgMQ3AgEIAQgYAwKCQYAxgQ8Af7/ÆACEAhgGEBAEAEAYHAwEAQBCAIQCAwgCACAQwDCAgDAÂGAgDGBgE7Af7/wAIQCDAYQGAgAIDgMDAIDAEM2BAI2DAQAI2BgMIDAcBAYDAcYCAw7A8/AxhAI2GhA2M2AÂyAgMA2ÂYw2YEAgM2G2AgE2DQgHGQEBAHGRg2G8A7/ÆAÂEAgHiEAPg2A+I4A+AcAfAQC2AHwACAQDxCAHx4AHx2APg8A7/w59A7/60AP5/Æ987A';

let dec = t => t.replace(/(\d+)([^\d])/g, (m, r, c) => new Array(+r + 1).join(c)).replace(/[¾µÀÁÂÃÄÅÆÇ]/g, i => i.charCodeAt(0) % 10);

console.log(dec(img).length);