p5.js TypedDict hasKey()用法及代碼示例

p5.js中p5.TypedDict的hasKey()方法用於檢查鍵入的字典中是否存在給定的鍵。如果給定鍵存在，則此方法返回true，否則返回false。鍵值對是一組相互映射的兩個值。可以通過使用該對的關鍵字部分查詢此字典來訪問這些值。一個類型化的字典可以存儲可以使用字典方法訪問的多個鍵-值對。

用法:

hasKey( key )

參數：此方法接受單個參數，如上所示和以下討論：

key:這是一個數字，表示必須在字典中檢查的 key 。

以下示例說明了p5.js中的hasKey()方法：

範例1：

Javascript

let y = 0; 
  
function setup() { 
  createCanvas(550, 500); 
  textSize(16); 
  
  text("Click the button to create a new " + 
       "dictionary or check if the keys exist", 
       20, 20); 
  
  text("Key:", 20, 260); 
  
  key_input = createInput('k0'); 
  key_input.position(70, 250); 
  key_input.size(40); 
  
  createBtn = createButton("Create dictionary"); 
  createBtn.position(30, 40); 
  createBtn.mouseClicked(createNewDict); 
  
  checkBtn = createButton("Check if the key exists"); 
  checkBtn.position(30, 290); 
  checkBtn.mouseClicked(checkVal); 
} 
  
function createNewDict() { 
  clear(); 
  
  // Create an object with random values 
  let obj = {}; 
  for (let i = 0; i < 5; i++) { 
    let rk = "k" + i; 
    let rn = "v" + i; 
    obj[rk] = rn; 
  
    text("Key:" + rk + "  Value:" + 
         rn, 40, 120 + 20 * i); 
  } 
  
  // Create a string dict using the above values 
  numDict = createStringDict(obj); 
  
  text("New Dictionary created with values", 
       20, 80); 
  
  text("Click the button to create a new " + 
       "dictionary or check if the keys exist", 
       20, 20); 
  
  text("Key:", 20, 260); 
} 
  
function checkVal() { 
  
  // Get the key to be checked 
  let keyToCheck = key_input.value(); 
  
  // Use hasKey() to check if the key exists 
  let hasEntry = numDict.hasKey(keyToCheck); 
  
  // If the key exists in the dictionary 
  if (hasEntry) { 
  
    let keyVal = numDict.get(keyToCheck); 
    
    text("The value at key:" + keyToCheck + 
         " is:" + keyVal, 20, 340 + y * 20); 
  } 
  
  // The key does not exist 
  else { 
    text("The key does not exist", 
         20, 340 + y * 20); 
  } 
  y++; 
  
  text("Click the button to create a new " + 
       "dictionary or check if the keys exist", 
       20, 20); 
  
  text("Key:", 20, 260); 
}

輸出：

範例2：

Javascript

function setup() { 
  createCanvas(550, 300); 
  textSize(16); 
  
  let stringDict = 
      createStringDict('Statue of Unity', 
                       '182 m'); 
  text("New string dictionary created " + 
       "with one key", 20, 20); 
  
  // Check if the specified key exists 
  let existOne = 
      stringDict.hasKey('Statue of Unity'); 
  text("Dictionary has key 'Statue of Unity':" + 
       existOne, 20, 60); 
  
  let existTwo = 
      stringDict.hasKey('Spring Temple Buddha'); 
  text("Dictionary has key " + 
       "'Spring Temple Buddha':" + 
       existTwo, 20, 100); 
  
  // Add the given key to the dictionary 
  // specifying the key and value 
  stringDict.create('Spring Temple Buddha', 
                    '128 m'); 
  text("New key 'Spring Temple Buddha' " + 
       "added with createKey()", 20, 140) 
  
  // Check if the specified key exists again 
  existTwo = 
    stringDict.hasKey('Spring Temple Buddha'); 
  text("Dictionary has key " + 
       "'Spring Temple Buddha':" + 
       existTwo, 20, 180); 
}

輸出：

在線編輯： https://editor.p5js.org/
環境設置： https://www.geeksforgeeks.org/p5-js-soundfile-object-installation-and-methods/
參考： https://p5js.org/reference/#/p5.TypedDict/hasKey

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注：本文由純淨天空篩選整理自sayantanm19大神的英文原創作品 p5.js TypedDict hasKey() Method。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。