String.prototype.startsWith.js 1.5 KB

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  1. try {
  2. var s = "foobar";
  3. assert(s.startsWith("f") === true);
  4. assert(s.startsWith("fo") === true);
  5. assert(s.startsWith("foo") === true);
  6. assert(s.startsWith("foob") === true);
  7. assert(s.startsWith("fooba") === true);
  8. assert(s.startsWith("foobar") === true);
  9. assert(s.startsWith("foobar1") === false);
  10. assert(s.startsWith("f", 0) === true);
  11. assert(s.startsWith("fo", 0) === true);
  12. assert(s.startsWith("foo", 0) === true);
  13. assert(s.startsWith("foob", 0) === true);
  14. assert(s.startsWith("fooba", 0) === true);
  15. assert(s.startsWith("foobar", 0) === true);
  16. assert(s.startsWith("foobar1", 0) === false);
  17. assert(s.startsWith("foo", []) === true);
  18. assert(s.startsWith("foo", null) === true);
  19. assert(s.startsWith("foo", undefined) === true);
  20. assert(s.startsWith("foo", false) === true);
  21. assert(s.startsWith("foo", true) === false);
  22. assert(s.startsWith("foo", "foo") === true);
  23. assert(s.startsWith("foo", -1) === true);
  24. assert(s.startsWith("foo", 42) === false);
  25. assert(s.startsWith("bar", 3) === true);
  26. assert(s.startsWith("bar", "3") === true);
  27. assert(s.startsWith("bar1", 3) === false);
  28. assert(s.startsWith() === false);
  29. assert(s.startsWith("") === true);
  30. assert(s.startsWith("", 0) === true);
  31. assert(s.startsWith("", 1) === true);
  32. assert(s.startsWith("", -1) === true);
  33. assert(s.startsWith("", 42) === true);
  34. console.log("PASS");
  35. } catch (e) {
  36. console.log("FAIL: " + e);
  37. }