How can I disable VSCode's suggestions for language keywords?

No, as of VS Code 1.21 you cannot filter out just the keyword suggestions in TypeScript and JavaScript.

Please file a feature request if you'd like to see this supported

Please note that you now need to use:

"[typescript]": {
  "editor.suggest.showKeywords": false
}

which deprecates:

"[typescript]": {
    "editor.suggest.filteredTypes": {
        "keyword": false
    }
}

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