Conditions | 17 |
Total Lines | 144 |
Code Lines | 107 |
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Small methods make your code easier to understand, in particular if combined with a good name. Besides, if your method is small, finding a good name is usually much easier.
For example, if you find yourself adding comments to a method's body, this is usually a good sign to extract the commented part to a new method, and use the comment as a starting point when coming up with a good name for this new method.
Commonly applied refactorings include:
If many parameters/temporary variables are present:
Complex classes like Modal.tsx ➔ Modal often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
1 | import React, { createContext, useContext, useEffect, useRef } from "react"; |
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21 | |||
22 | export default function Modal({ |
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23 | id, |
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24 | parentElement, |
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25 | visible, |
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26 | children, |
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27 | className, |
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28 | onModalConfirm, |
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29 | onModalMiddle, |
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30 | onModalCancel, |
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31 | }: ModalProps): React.ReactPortal | null { |
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32 | // Set up div ref to measure modal height |
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33 | const modalRef = useRef<HTMLDivElement>(null); |
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34 | |||
35 | const getFocusableModalElements = () => |
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36 | modalRef && modalRef.current ? getFocusableElements(modalRef.current) : []; |
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37 | |||
38 | const handleTabKey = (e: KeyboardEvent): void => { |
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39 | if (modalRef && modalRef.current) { |
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40 | const focusableModalElements = getFocusableModalElements(); |
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41 | |||
42 | if (focusableModalElements.length === 0) { |
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43 | e.preventDefault(); // TODO: should this throw an error? |
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44 | return; |
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45 | } |
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46 | |||
47 | const firstElement = focusableModalElements[0] as HTMLElement; |
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48 | const lastElement = focusableModalElements[ |
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49 | focusableModalElements.length - 1 |
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50 | ] as HTMLElement; |
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51 | |||
52 | if (focusableModalElements.length === 1) { |
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53 | // This check to avoid strange behaviour if firstElement == lastElement. |
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54 | firstElement.focus(); |
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55 | e.preventDefault(); |
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56 | return; |
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57 | } |
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58 | |||
59 | const focusableModalElementsArray = Array.from(focusableModalElements); |
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60 | |||
61 | if ( |
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62 | document.activeElement && |
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63 | !focusableModalElementsArray.includes( |
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64 | document.activeElement as HTMLElement, |
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65 | ) |
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66 | ) { |
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67 | firstElement.focus(); |
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68 | e.preventDefault(); |
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69 | return; |
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70 | } |
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71 | |||
72 | if (!e.shiftKey && document.activeElement === lastElement) { |
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73 | firstElement.focus(); |
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74 | e.preventDefault(); |
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75 | return; |
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76 | } |
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77 | |||
78 | if (e.shiftKey && document.activeElement === firstElement) { |
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79 | lastElement.focus(); |
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80 | e.preventDefault(); |
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81 | } |
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82 | } |
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83 | }; |
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84 | |||
85 | // Collection of key codes and event listeners |
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86 | const keyListenersMap = new Map([ |
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87 | [27, onModalCancel], |
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88 | [9, handleTabKey], |
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89 | ]); |
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90 | |||
91 | // Runs every time visible changes to set the overflow on the modal and update the body overflow |
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92 | useEffect((): (() => void) => { |
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93 | function setBodyStyle(): void { |
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94 | document.body.style.overflow = visible ? "hidden" : "visible"; |
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95 | } |
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96 | setBodyStyle(); |
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97 | // Runs on component unmount |
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98 | return (): void => { |
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99 | setBodyStyle(); |
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100 | }; |
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101 | }, [visible]); |
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102 | |||
103 | // Adds various key commands to the modal |
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104 | useEffect((): (() => void) => { |
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105 | let keyListener; |
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106 | if (visible) { |
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107 | keyListener = (e: KeyboardEvent): void => { |
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108 | const listener = keyListenersMap.get(e.keyCode); |
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109 | return listener && listener(e); |
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110 | }; |
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111 | document.addEventListener("keydown", keyListener); |
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112 | } |
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113 | |||
114 | return (): void => { |
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115 | if (keyListener !== undefined) { |
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116 | document.removeEventListener("keydown", keyListener); |
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117 | } |
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118 | }; |
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119 | }, [keyListenersMap, visible]); |
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120 | |||
121 | // Focus the first focusable element when the modal becomes visible. |
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122 | useEffect(() => { |
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123 | if (visible) { |
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124 | const focusableModalElements = getFocusableModalElements(); |
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125 | if (focusableModalElements.length > 0) { |
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126 | const firstElement = focusableModalElements[0] as HTMLElement; |
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127 | firstElement.focus(); |
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128 | } |
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129 | } |
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130 | }, [visible]); |
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131 | |||
132 | if (parentElement !== null) { |
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133 | return createPortal( |
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134 | <div |
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135 | aria-describedby={`${id}-description`} |
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136 | aria-hidden={!visible} |
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137 | aria-labelledby={`${id}-title`} |
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138 | data-c-dialog={visible ? "active--overflowing" : ""} |
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139 | data-c-padding="top(double) bottom(double)" |
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140 | role="dialog" |
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141 | ref={modalRef} |
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142 | className={className} |
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143 | data-c-visibility={!visible ? "hidden" : ""} |
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144 | > |
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145 | <div data-c-background="white(100)" data-c-radius="rounded"> |
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146 | <modalContext.Provider |
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147 | value={{ |
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148 | id, |
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149 | parentElement, |
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150 | visible, |
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151 | onModalConfirm, |
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152 | onModalMiddle, |
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153 | onModalCancel, |
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154 | }} |
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155 | > |
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156 | {children} |
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157 | </modalContext.Provider> |
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158 | </div> |
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159 | </div>, |
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160 | parentElement, |
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161 | ); |
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162 | } |
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163 | |||
164 | return null; |
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165 | } |
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247 |