SpiderMonkey 1.8.5
ameter js_getgcparameterforthread js_getglobalforscopechain js_getinternedstringchars js_getinternedstringcharsandlength js_getownpropertydescriptor js_getpropertyattrsgetterandsetterbyid js_getpropertybyid js_getpropertybyiddefault js_getpropertydefault js_getpropertydescriptorbyid js_getruntimesecuritycallbacks js_getsecuritycallbacks js_getstringcharsandlength js_getstringcharsz js_getstringcharszandlength js_getstringencodinglength js_haspropertybyid js_initctypesclass js_internjsstring js_isconstructing_possiblywithgiventhisobject js_isextensible js_isinrequest js_leavecrosscompartmentcall js_lookuppropertybyid js_lookuppropertywithflagsbyid js_new js_newcompartmentandglobalobject js_newdateobject js_newdateobjectmsec js_newfunctionbyid body new c++ helpers while jsapi remains a ...
...additionally, js_newstring, js_getstringbytes, and js_getstringchars were removed, replaced by fallible interfaces like js_getstringcharszandlength and js_encodestringtobuffer (not an exhaustive list).

SpiderMonkey 1.8.7
ameter js_getgcparameterforthread js_getglobalforscopechain js_getinternedstringchars js_getinternedstringcharsandlength js_getownpropertydescriptor js_getpropertyattrsgetterandsetterbyid js_getpropertybyid js_getpropertybyiddefault js_getpropertydefault js_getpropertydescriptorbyid js_getruntimesecuritycallbacks js_getsecuritycallbacks js_getstringcharsandlength js_getstringcharsz js_getstringcharszandlength js_getstringencodinglength js_haspropertybyid js_initctypesclass js_internjsstring js_isconstructing_possiblywithgiventhisobject js_isextensible js_isinrequest js_leavecrosscompartmentcall js_lookuppropertybyid js_lookuppropertywithflagsbyid js_new js_newcompartmentandglobalobject js_newdateobject js_newdateobjectmsec js_newfunctionbyid body new c++ helpers while jsapi remains a ...
...additionally, js_newstring, js_getstringbytes, and js_getstringchars were removed, replaced by fallible interfaces like js_getstringcharszandlength and js_encodestringtobuffer (not an exhaustive list).

JSAPI reference
solete since jsapi 1.8.5 js_newgrowablestring obsolete since jsapi 27 js_getstringbytes obsolete since jsapi 1.8.5 js_getstringbytesz obsolete since jsapi 1.8.5 js_getstringchars obsolete since jsapi 1.8.5 js_getstringcharsz obsolete since jsapi 33 js_getstringcharsandlength added in jsapi 1.8.5 obsolete since jsapi 33 js_getstringcharsz added in spidermonkey 1.8.5 obsolete since jsapi 33 js_getstringcharszandlength added in spidermonkey 1.8.5 obsolete since jsapi 33 js_getflatstringchars obsolete since jsapi 33 js_makestringimmutable obsolete since javascript 1.8.5 js_encodecharacters obsolete since jsapi 19 js_cstringsareutf8 obsolete since jsapi 19 js_setcstringsareutf8 obsolete since jsapi 19 interning strings tells the spidermonkey engine to reuse existing string objects when possible.

SpiderMonkey 38
t32 (bug 1112774) js_enumeratestub (bug 1103152) js_evaluatescript (bug 1100579) js_evaluateucscript (bug 1100579) js_executescriptversion (bug 1095660) js_getflatstringchars (bug 1037869) js_getfunctioncallback (bug 1103269) js_getinternedstringchars (bug 1037869) js_getinternedstringcharsandlength (bug 1037869) js_getstringcharsandlength (bug 1037869) js_getstringcharsz (bug 1037869) js_getstringcharszandlength (bug 1037869) js_gettypename (bug 1037718) js_isabouttobefinalized (bug 650161) js_lookupelement (bug 1094176) js_lookupproperty (bug 1094176) js_lookuppropertybyid (bug 1094176) js_lookupucproperty (bug 1094176) js_newpropertyiterator (bug 1081660) js_nextproperty (bug 1081660) js_resolvestub (bug 1103152) js_setfinalizecallback (bug 996785) js_setfunctioncallback (bug 1103269) jscha...