Test if a string contains valid JSON. Characters vectors will be collapsed into a single string.
validate(txt)#Output from toJSON and serializeJSON should pass validation
myjson <- toJSON(mtcars)
validate(myjson) #TRUE
#> [1] TRUE
#Something bad happened
truncated <- substring(myjson, 1, 100)
validate(truncated) #FALSE
#> [1] FALSE
#> attr(,"offset")
#> [1] 1
#> attr(,"err")
#> [1] "parse error: premature EOF\n [{\"mpg\":21,\"cyl\":6,\"disp\":160,\"\n (right here) ------^\n"