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| 1 | +alert("Strings in JavaScript!"); |
| 2 | + |
| 3 | +/* |
| 4 | + JavaScript Strings |
| 5 | + Strings are for storing text |
| 6 | + |
| 7 | + Strings are written with quotes |
| 8 | + |
| 9 | + Using Quotes |
| 10 | + A JavaScript string is zero or more characters written inside quotes. |
| 11 | +*/ |
| 12 | + // Example |
| 13 | + let text = "John Doe"; |
| 14 | + |
| 15 | + // You can use single or double quotes: |
| 16 | + |
| 17 | + // Example |
| 18 | + let carName1 = "Volvo XC60"; // Double quotes |
| 19 | + let carName2 = 'Volvo XC60'; // Single quotes |
| 20 | +/* |
| 21 | + Note |
| 22 | + Strings created with single or double quotes works the same. |
| 23 | + There is no difference between the two. |
| 24 | + |
| 25 | + Quotes Inside Quotes |
| 26 | + - You can use quotes inside a string, as long as they don't match the quotes surrounding the string: |
| 27 | +*/ |
| 28 | + // Example |
| 29 | + let answer1 = "It's alright"; |
| 30 | + let answer2 = "He is called 'Johnny'"; |
| 31 | + let answer3 = 'He is called "Johnny"'; |
| 32 | + |
| 33 | +/* |
| 34 | + Template Strings |
| 35 | + - Templates were introduced with ES6 (JavaScript 2016). |
| 36 | + - Templates are strings enclosed in backticks (`This is a template string`). |
| 37 | + - Templates allow single and double quotes inside a string: |
| 38 | +*/ |
| 39 | + // Example |
| 40 | + let text1 = `He's often called "Johnny"`; |
| 41 | +/* |
| 42 | + Note: Templates are not supported in Internet Explorer. |
| 43 | + |
| 44 | + String Length |
| 45 | + - To find the length of a string, use the built-in length property: |
| 46 | +*/ |
| 47 | + // Example |
| 48 | + let text2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; |
| 49 | + let length = text.length; |
| 50 | +/* |
| 51 | + Escape Characters |
| 52 | + - Because strings must be written within quotes, JavaScript will misunderstand this string: |
| 53 | + |
| 54 | + let text3 = "We are the so-called "Vikings" from the north."; |
| 55 | + |
| 56 | + The string will be chopped to "We are the so-called ". |
| 57 | + To solve this problem, you can use an backslash escape character. |
| 58 | + The backslash escape character (\) turns special characters into string characters: |
| 59 | + |
| 60 | + Code Result Description |
| 61 | + \' ' Single quote |
| 62 | + \" " Double quote |
| 63 | + \\ \ Backslash |
| 64 | + |
| 65 | +*/ |
| 66 | + // Examples |
| 67 | + // \" inserts a double quote in a string: |
| 68 | + let text4 = "We are the so-called \"Vikings\" from the north."; |
| 69 | + |
| 70 | + // \' inserts a single quote in a string: |
| 71 | + let text5 = 'It\'s alright.'; |
| 72 | + |
| 73 | + // \\ inserts a backslash in a string: |
| 74 | + let text6 = "The character \\ is called backslash."; |
| 75 | + |
| 76 | + |
| 77 | + |
| 78 | +// JavaScript String Methods |
| 79 | + |
| 80 | + let myString = 'I\'m a "fun" string'; |
| 81 | + document.write("String: " + myString + "<br />"); |
| 82 | + |
| 83 | + // JavaScript String Length |
| 84 | + // The length property returns the length of a string: |
| 85 | + document.write("<br />" + "String Length: " + myString.length); |
| 86 | + |
| 87 | + // JavaScript Uppercase |
| 88 | + document.write("<br />" + "String to uppercase: " + myString.toUpperCase()); |
| 89 | + |
| 90 | + // JavaScript Lowercase |
| 91 | + document.write("<br />" + "String to lowercase: " + myString.toLowerCase()); |
| 92 | + |
| 93 | + // Javascript string find index |
| 94 | + document.write("<br />" + "Word 'fun' index: " + myString.indexOf("fun")); |
| 95 | + |
| 96 | + // Javascript string find index thrw -1 for not found strings |
| 97 | + document.write("<br />" + "Word 'apple' index: " + myString.indexOf("apple")); // This apple is not in myString string variable. |
| 98 | + |
| 99 | + if(myString.indexOf("apple") === -1){ |
| 100 | + |
| 101 | + document.write("<br />The word 'apple' is not in the string"); |
| 102 | + |
| 103 | + } else { |
| 104 | + |
| 105 | + document.write("<br />The word 'apple' starts at position" + myString.indexOf("apple")); |
| 106 | + |
| 107 | + } |
| 108 | + |
| 109 | + |
| 110 | + let string1 = "abc"; |
| 111 | + let string2 = "bcd"; |
| 112 | + let string3 = "abc"; |
| 113 | + let string4 = "ABC"; |
| 114 | + |
| 115 | + console.log(string1 === string2); |
| 116 | + console.log(string1 === string3); |
| 117 | + console.log(string1 === string4); |
| 118 | + |
| 119 | + console.log(string1 < string4); |
| 120 | + console.log(string1 > string4); // In JavaScript Uppercase letters are smaller than lowercase letters. |
| 121 | + |
| 122 | + |
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