数値の文字列をパースしよう

Transcript

1. ਺஋ͷจࣈྻΛύʔε͠Α͏ Niigata 5min Tech #9 @circled9 1
2. ࣗݾ঺հ @circled9 দҪɹਖ਼ࢤ / Matsui Masashi גࣜձࣾϞχΫϧ TypeScriptͰ৭ʑܭࢉ͢Δ࢓ࣄΛ ͯ͠·͢ 2
3. ਺஋ͷจࣈྻͷύʔε • JavaScriptͰ਺஋ͷจࣈྻͷύʔε͠·͢ΑͶʁ • parseInt, parseFloat, NumberͷͲΕ࢖͑͹͍͍͔೰Έ·ͤΜ ͔ʁ • ͱ͍͏Θ͚Ͱ৭ʑύʔεͯ͠Έ·ͨ͠ 3
4. ੔਺ 4
5. "123" 5
6. ී௨ͷ੔਺ͷ৔߹ > parseInt("123") <- 123 > parseFloat("123") <- 123 > Number("123") <- 123 6
7. "123,456" 7
8. ܻ̏۠੾Γͷ੔਺ͷ৔߹ > parseInt("123,456") <- 123 > parseFloat("123,456") <- 123 > Number("123,456") <- NaN 8
9. "123_456" 9
10. Numeric Separator • ES2021ͷه๏ • ਺஋ͷ۠੾Γจࣈͱͯ͠ΞϯμʔείΞ͕࢖͑Δ > 123_456_789 <- 123456789 10
11. ΞϯμʔείΞ۠੾Γͷ੔਺ͷ৔߹ > parseInt("123_456") <- 123 > parseFloat("123_456") <- 123 > Number("123_456") <- NaN 11
12. ੔਺ͷ·ͱΊ • parseIntͱparseFloat͸਺஋Ҏ֎ͷจࣈ͕ग़ͯ͘Δ·Ͱύʔε͢ Δ • Number͸มͳจࣈ͕͋ΔͱNaNΛฦ͢ 12
13. খ਺ 13
14. "1.23" 14
15. ී௨ͷখ਺ͷ৔߹ > parseInt("1.23") <- 1 > parseFloat("1.23") <- 1.23 > Number("1.23") <- 1.23 15
16. ".123" 16
17. খ਺ͷলུܗͷ৔߹ > parseInt(".123") <- NaN > parseFloat(".123") <- 0.123 > Number(".123") <- 0.123 17
18. "192.168.1.1" 18
19. খ਺Ͱ͸ͳ͍Կ͔ͩͬͨ৔߹ > parseInt("192.168.1.1") <- 192 > parseFloat("192.168.1.1") <- 192.168 > Number("192.168.1.1") <- NaN 19
20. খ਺ͷ·ͱΊ • parseInt͸਺஋Ҏ֎ͷจࣈ͕ग़ͯ͘Δ·Ͱύʔε͢Δ • parseFloat͸খ਺ͱͯ͠ύʔεͰ͖Δͱ͜Ζ·Ͱύʔε͢Δ • Number͸খ਺ͱ͓͔͍ͯ͠͠৔߹͸NaNΛฦ͢ 20
21. ͦͷଞͷ਺ 21
22. "1.234E-5" 22
23. ࢦ਺දهͷ৔߹ > parseInt("1.234E-5") <- 1 > parseFloat("1.234E-5") <- 0.00001234 > Number("1.234E-5") <- 0.00001234 23
24. "Infinity" 24
25. In fi nityͷ৔߹ > parseInt("-Infinity") <- NaN > parseFloat("-Infinity") <- -Infinity > Number("-Infinity") <- -Infinity 25
26. " 123 " 26
27. લޙʹۭന͕͋Δ৔߹ > parseInt(" 123 ") <- 123 > parseFloat(" 123 ") <- 123 > Number(" 123 ") <- 123 27
28. " 1 2 3 " 28
29. ్தʹۭന͕͋Δ৔߹ > parseInt(" 1 2 3 ") <- 1 > parseFloat(" 1 2 3 ") <- 1 > Number(" 1 2 3 ") <- NaN 29
30. ͦͷଞͷ਺ͷ·ͱΊ • parseFloat΋Number΋ࢦ਺දه΍InfinityʹରԠ͍ͯ͠Δ • Ͳͷؔ਺΋จࣈྻͷલޙͷۭന͸ແࢹ͢Δ • Ͳͷؔ਺΋จࣈྻͷ్தͷۭന͸ύʔεͰ͖ͳ͍จࣈѻ͍ʹͳΔ 30
31. ۭͷ஋ 31
32. "" 32
33. ۭจࣈͷ৔߹ > parseInt("") <- NaN > parseFloat("") <- NaN > Number("") <- 0 33
34. null 34
35. nullͷ৔߹ > parseInt(null) <- NaN > parseFloat(null) <- NaN > Number(null) <- 0 35
36. undefined 36
37. unde fi nedͷ৔߹ > parseInt(undefined) <- NaN > parseFloat(undefined) <- NaN > Number(undefined) <- NaN 37
38. ۭͷ஋ͷ·ͱΊ • Number͸ۭനจࣈͱnullΛύʔε͢Δͱ0Λฦ͢ • ҰํɺparseIntͱparseFloat͸NaNΛฦ͢ • Ͳͷؔ਺΋undefinedΛύʔε͢ΔͱNaNΛฦ͢ 38
39. ·ͱΊ 39
40. ·ͱΊ • parseInt͸਺ࣈͷ෦෼ΛͰ͖Δ͚ͩύʔε͢Δ • parseFloat͸খ਺ͬΆ͍෦෼ΛͰ͖Δ͚ͩύʔε͢Δ • Number͸มͳจࣈ͕ೖͬͯΔͱNaNΛฦ͢ • Numberͷۭനจࣈͱnullͷڍಈʹ஫ҙ 40
41. ͓·͚ 41
42. ͜ΕΒ͸Ұॹ > parseInt === Number.parseInt <- true > parseFloat === Number.parseFloat <- true 42
43. ͜Ε΋Ұॹ > +"" === Number("") <- true 43