3 ms·

Try/catch/finally is handled by TurboFan (one of V8's optimizing compilers) - see https://groups.google.com/forum/#!topic/v8-users/maH60gh_a8s https://groups.go

Try/catch/finally is handled by TurboFan (one of V8's optimizing compilers) - see https://groups.google.com/forum/#!topic/v8-users/maH60gh_a8s https://groups.google.com/forum/#!topic/v8-users/maH60gh_a8s for more detail. There is a certain set of features which go through TurboFan instead of CrankShaft (the other optimizing compiler). Disclaimer: I work on the V8 team.

pygy_ 10y ago
Still, using `try` seems much slower (in Chrome 52): var times = [[],[]] var sums = [0, 0] var funcs = [ function(){ sums[0]+=1 }, function(){try{ sums[1]+=1 }catch(e){}} ] function bench(n){ var t0 = performance.now() for(var i = 0; i< 30000; i++) funcs[n]() times[n].push(performance.now()-t0) } for(var j = 0; j< 10000; j++) bench(j%2) function avg(ary){return ary.reduce(function(acc, v){return acc+v}, 0)/ary.length} console.log(times.map(avg)) // results: // [bare , wrapped in try{} ] // VM89:18 [0.347546000033617, 0.7464809999451041] Let's do some more work inside the function / try block: var times = [[],[]] var sums = [0, 0] var funcs = [ function(){ for (var i = 0; i < 1000; i++) sums[0]+=1 }, function(){try{ for (var i = 0; i < 1000; i++) sums[1]+=1 }catch(e){}} ] function bench(n){ var t0 = performance.now() for(var i = 0; i< 30; i++) funcs[n]() times[n].push(performance.now()-t0) } for(var j = 0; j< 10000; j++) bench(j%2) function avg(ary){return ary.reduce(function(acc, v){return acc+v}, 0)/ary.length} console.log(times.map(avg)) // results: // [bare , wrapped in try{} ] // VM90:18 [0.09457900004982948, 0.5069960000008344] I'm sure I'm doing many things wrong since I'm not a JS perf expert, but still, the difference here is goes from 2 to 50 times slower with the `try` block... Edit: for the sake of completeness, on the same machine: Firefox gives [10.2, 10.3] and [5.30, 5.45] Safari gives [5.56, 5.60] and [4.91, 4.94]

pygy_ 10y ago

Still, using `try` seems much slower (in Chrome 52): var times = [[],[]] var sums = [0, 0] var funcs = [ function(){ sums[0]+=1 }, function(){try{ sums[1]+=1 }catch(e){}} ] function bench(n){ var t0 = performance.now() for(var i = 0; i< 30000; i++) funcs[n]() times[n].push(performance.now()-t0) } for(var j = 0; j< 10000; j++) bench(j%2) function avg(ary){return ary.reduce(function(acc, v){return acc+v}, 0)/ary.length} console.log(times.map(avg)) // results: // [bare , wrapped in try{} ] // VM89:18 [0.347546000033617, 0.7464809999451041] Let's do some more work inside the function / try block: var times = [[],[]] var sums = [0, 0] var funcs = [ function(){ for (var i = 0; i < 1000; i++) sums[0]+=1 }, function(){try{ for (var i = 0; i < 1000; i++) sums[1]+=1 }catch(e){}} ] function bench(n){ var t0 = performance.now() for(var i = 0; i< 30; i++) funcs[n]() times[n].push(performance.now()-t0) } for(var j = 0; j< 10000; j++) bench(j%2) function avg(ary){return ary.reduce(function(acc, v){return acc+v}, 0)/ary.length} console.log(times.map(avg)) // results: // [bare , wrapped in try{} ] // VM90:18 [0.09457900004982948, 0.5069960000008344] I'm sure I'm doing many things wrong since I'm not a JS perf expert, but still, the difference here is goes from 2 to 50 times slower with the `try` block... Edit: for the sake of completeness, on the same machine: Firefox gives [10.2, 10.3] and [5.30, 5.45] Safari gives [5.56, 5.60] and [4.91, 4.94]