typescript --allowJs too slow

[viktor-nikolaev]

TypeScript Version:

1.8.9

tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "module": "amd",
    "noEmitOnError": true,
    "allowJs": true
  },
  "exclude": [
    "node_modules",
    "bower_components"
  ]
}

gulp task

var  ts = require("gulp-typescript"),

var tsProject = ts.createProject("tsconfig.json", {
    noExternalResolve: true,
    typescript: require("typescript")
});

gulp.task("scripts", function() {
    return gulp.src(paths.devroot.ts)
        .pipe(ts(tsProject))
        .pipe(gulp.dest(paths.webroot.app));
});

gulp.task("watch", ["scripts"], function() {
    gulp.watch(paths.devroot.ts, ["scripts"]);
})

When I run the task with --allowJs set to true, it takes about 10seconds to build my project. Moreover it takes 10 seconds after any change in my files, ie it is not incrementaly.

When --allowJs is disabled, it takes about 1 second to build the whole project, and 100ms to build incrementally.

[mhegazy]

can you run tsc --diagnistics --listFiles with and without --allowJs and share the output?

[viktor-nikolaev]

@mhegazy , i ran it in a working pc, that a bit faster.
Actually, the main problem is with "-watch".

diag.allowJs.txt
diag.disallowJs.txt

diag.allowJs.watch.txt
diag.disallowJs.watch.txt

[mhegazy]

in the allowJS case, you are pulling in many more files (244 vs. 50). we are spending 2 more seconds in additional IO (reading the extra files, and writing their output) and 2 more seconds in type checking them see below.

without --allowJs

Files:             244
Lines:           54431
Nodes:          260098
Identifiers:     88870
Symbols:       7629718
Types:           11834
Memory used:   143379K
I/O read:        0.06s
I/O write:       1.99s
Parse time:      0.86s
Bind time:       0.40s
Check time:      2.17s
Emit time:       2.63s
Total time:      6.07s

No --allowJs

Files:              50
Lines:           24110
Nodes:           97627
Identifiers:     37579
Symbols:       1158822
Types:            6640
Memory used:    69853K
I/O read:        0.01s
I/O write:       0.07s
Parse time:      0.32s
Bind time:       0.26s
Check time:      0.78s
Emit time:       0.21s
Total time:      1.57s

The question is do you intend to include these files in your compilation? if no, then you should add App_Scripts to your exclude in tsconfig.json.