JavaScript でよく使用される 20 の文字列メソッド (コレクション)

    //charAt(x)
    var myString = 'jQuery FTW!!!';
    console.log(myString.charAt(7));
    //output: F

`charCodeAt(x)`返回字符串中`x`位置处字符的`unicode`值。

    //charAt(position)
    var message="jquery4u"
    //alert "113"
    alert(message.charAt(1)

    //concat(v1, v2,..)
    var message="Sam"
    var final=message.concat(" is a"," hopeless romantic.")
    //alerts "Sam is a hopeless romantic."
    alert(final)

    //fromCharCode(c1, c2,...)
    console.log(String.fromCharCode(97,98,99,120,121,122))
    //output: abcxyz
    console.log(String.fromCharCode(72,69,76,76,79))
    //output: HELLO

    //indexOf(char/substring)
    var sentence="Hi, my name is Sam!"
    if (sentence.indexOf("Sam")!=-1)
    alert("Sam is in there!")

    //lastIndexOf(substr, [start])
    var myString = 'javascript rox';
    console.log(myString.lastIndexOf('r'));
    //output: 11

    //match(regexp) //select integers only
    var intRegex = /[0-9 -()+]+$/;  
     
    var myNumber = '999';
    var myInt = myNumber.match(intRegex);
    console.log(isInt);
    //output: 999
     
    var myString = '999 JS Coders';
    var myInt = myString.match(intRegex);
    console.log(isInt);
    //output: null

    //replace(substr, replacetext)
    var myString = '999 JavaScript Coders';
    console.log(myString.replace(/JavaScript/i, "jQuery"));
    //output: 999 jQuery Coders
     
    //replace(regexp, replacetext)
    var myString = '999 JavaScript Coders';
    console.log(myString.replace(new RegExp( "999", "gi" ), "The"));
    //output: The JavaScript Coders

    //search(regexp)
    var intRegex = /[0-9 -()+]+$/;  
     
    var myNumber = '999';
    var isInt = myNumber.search(intRegex);
    console.log(isInt);
    //output: 0

    //slice(start, end)
    var text="excellent"
    text.slice(0,4) //returns "exce"
    text.slice(2,4) //returns "ce"

    //substring(from, to)
    var text="excellent"
    text.substring(0,4) //returns "exce"
    text.substring(2,4) //returns "ce"

    //substring(from, [to])
    var myString = 'javascript rox';
    myString = myString.substring(0,10);
    console.log(myString)
    //output: javascript

    //toLowerCase()
    var myString = 'JAVASCRIPT ROX';
    myString = myString.toLowerCase();
    console.log(myString)
    //output: javascript rox

    //toUpperCase()
    var myString = 'javascript rox';
    myString = myString.toUpperCase();
    console.log(myString)
    //output: JAVASCRIPT ROX

    //includes()
    var mystring = "Hello, welcome to edureka";
    var n = mystring.includes("edureka");
    //output: True

    //endsWith()
    var mystr = "List of javascript functions";
    var n = mystr.endsWith("functions");
    //output: True

    //repeat()
    var string = "Welcome to Edureka";
    string.repeat(2);
    //output: Welcome to Edureka Welcome to Edureka

    //valueOf()
    var mystr = "Hello World!";
    var res = mystr.valueOf();
    //output: Hello World!