常用API——字元串String型函數

上圖：

• 聲明

var myString = new String(“Every good boy does fine.”);

var myString = “Every good boy does fine.”;

• 字元串連接

var myString = “Every ” + “good boy ” + “does fine.”;

var myString = “Every “; myString += “good boy does fine.”;

• 截取字元串

//截取第 6 位開始的字元

var myString = “Every good boy does fine.”;

var section = myString.substring(6); //結果: “good boy does fine.”

//截取第 0 位開始至第 10 位為止的字元

var myString = “Every good boy does fine.”;

var section = myString.substring(0,10); //結果: “Every good”

//截取從第 11 位到倒數第 6 位為止的字元

var myString = “Every good boy does fine.”;

var section = myString.slice(11,-6); //結果: “boy does”

//從第 6 位開始截取長度為 4 的字元

var myString = “Every good boy does fine.”;

var section = myString.substr(6,4); //結果: “good”

• 轉換大小寫

var myString = “Hello”;

var lcString = myString.toLowerCase(); //結果: “hello”

var ucString = myString.toUpperCase(); //結果: “HELLO”

• 字元串比較

var aString = “Hello!”;

var bString = new String(“Hello!”);

if( aString == “Hello!” ){ } //結果: true

if( aString == bString ){ } //結果: true

if( aString === bString ){ } //結果: false (兩個對象不同,儘管它們的值相同)

• 檢索字元串

var myString = “hello everybody.”;

// 如果檢索不到會返回-1,檢索到的話返回在該串中的起始位置

if( myString.indexOf(“every”) > -1 ){ } //結果: true

• 查找替換字元串

var myString = “I is your father.”;

var result = myString.replace(“is”,”am”); //結果: “I am your father.”

• 特殊字元

  • \b : 後退符
  • \t : 水平製表符
  • \n : 換行符
  • \v : 垂直製表符
  • \f : 分頁符
  • \r : 回車符
  • \” : 雙引號
  • \’ : 單引號
  • \ 反斜桿

• 將字元轉換成Unicode編碼

var myString = “hello”;

var code = myString.charCodeAt(3); //返回”l”的Unicode編碼(整型)

var char = String.fromCharCode(66); //返回Unicode為66的字元

• 將字元串轉換成URL編碼

var myString = “hello all”;

var code = encodeURI(myString); //結果: “hello%20all”

var str = decodeURI(code); //結果: “hello all”

//相應的還有: encodeURIComponent() decodeURIComponent()