Javascript

Reserved Keyword In Javascript?

Javascript has a Predefined Collection of reserved keywords that can not be used as variables Name, Labels or Function, and Class Name.

Reserved Keyword In Javascript?

ECMA Script: 1

1. break
2. catch
3. case
4. class
5. const
6. continue
7. debugger
8. default
9. delete
10. do
11. else
12. enum
13. export
14. extends
15. false
16. finally
17. for
18. function
19. if
20. import
21. in
22. new
23. null
24. return
25. super
26. switch
27. this
28. throw
29. true
30. try
31. typeof
32. var
33. void
34. while
35. with

ECMA Script: 2

Add 24 additional reserved keywords in javascript.

New keywords denote by *

1. abstract*
2. boolean*
3. break*
4. byte*
5. case*
6. catch*
7. char*
8. class
9. const*
10. continue*
11. debugger
12. default*
13. delete*
14. do*
15. double
16. else*
17. enum
18. export
19. extends
20. false*
21. final*
22. finally*
23. float*
24. for*
25. function*
26. goto*
27. if
28. implements
29. import
30. in
31. instanceof*
32. int*
33. interface*
34. long*
35. native*
36. new
37. null
38. package*
39. private*
40. protected*
41. public*
42. return
43. short*
44. static*
45. super
46. switch
47. synchronized*
48. this
49. throw
50. throws*
51. transient*
52. true
53. try
54. typeof
55. var
56. void
57. volatile*
58. while
59. with

ECMA Script: 5

No change since ECMAScript 3

ECMAScript 5 remove int, char, goto, long, final, float, short, double, native, throws, boolean, abstract, volatile, transient, and synchronized.

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Two additional reserved keywords in javascript.

1. break
2. catch
3. case
4. class
5. const
6. continue
7. debugger
8. default
9. delete
10. do
11. else
12. enum
13. export
14. extends
15. false
16. finally
17. for
18. function
19. if
20. implements
21. import
22. in
23. instanceof
24. interface
25. let*
26. new
27. null
28. package
29. private
30. protected
31. public
32. return
33. static
34. super
35. switch
36. this
37. throw
38. true
39. try
40. typeof
41. var
42. void
43. while
44. with
45. yield*

ECMA Script: 6

1. await
2. break
3. case
4. catch
5. class
6. const
7. continue
8. debugger
9. default
10. delete
11. do
12. else
13. export
14. extends
15. finally
16. for
17. function
18. if
19. import
20. in
21. instanceof
22. new
23. return
24. super
25. switch
26. this
27. throw
28. try
29. typeof
30. var
31. void
32. while
33. with
34. yield

Note:

The following keywords are not reserved, but when you use strict mode on javascript, that time shows an error.

1. implements
2. interface
3. let
4. package
5. private
6. protected
7. public
8. static

Other:

1. true
2. false
3. null
4. undefined

Reference:

• https://www.w3schools.com/js/js_reserved.asp

Wrong

"use strict"
function true(){}  //Show Error In Strict Mode
let await = 'rajdeep singh';  //  Show Error with and without Strict Mode
let case = 122  // Show Error with and without Strict Mojavade

Javascript SyntaxError

Conclusion

Javascript reserved keywords can not be used as a variable Name, Label or Function, and Class Name when using a named variable that shows SyntaxError.

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