SOURCE

var welcomeString="welcome";
document.write(welcomeString+"<br\>");
document.write(welcomeString.length+"<br\>");
document.write("================"+"<br\>");

function writeDocument(variable) {
    document.write(variable + "<br/>");
} 

var welcomeString="welcome";
writeDocument(welcomeString);
writeDocument(welcomeString.length);
writeDocument(welcomeString.toLowerCase);
writeDocument(welcomeString.toUpperCase);
writeDocument(welcomeString.charAt(2));
writeDocument(welcomeString.charAt(6));
writeDocument(welcomeString.substring(3));
writeDocument(welcomeString.substring(0,2));
document.write("================"+"<br\>");

var sentence="we are chinese man and good and yy";
writeDocument(sentence);
writeDocument(sentence.replace("we","we们"));
writeDocument(sentence.replace(/man/g,"girl"));
document.write("================"+"<br\>");

var splitSemtence="we have fun in our class"
writeDocument(splitSemtence);
writeDocument(splitSemtence.split(" "));
writeDocument(welcomeString);
writeDocument(welcomeString.split(""));
writeDocument(sentence.split(""))
document.write("================"+"<br\>")
;
writeDocument(sentence.indexOf("and"));//首次出现
writeDocument(sentence.lastIndexOf("and"));//最后出现
writeDocument(sentence.match("and"));
writeDocument(sentence.match(/and/g));
writeDocument(sentence.search(/and/g));
document.write("================"+"<br\>")

//如何找出字符串“Can you can a can as a Canner can can a can”中
//找出所有c的个数，不区分大小写。 
str="Can you can a can as a Canner can can a can";
function countChar(stringValue,char){
    var charCount=0;
    for(var i=0;i<stringValue.length;i++){
        if(stringValue.charAt(i).toLowerCase()==char){//toLowerCase转小写
            ++charCount;
        }
    }
    return charCount;
}
writeDocument("there are"+countChar(str,"c")+"c in sentence");
document.write("================"+"<br\>")

function sz(str){
    var t=0;
    for(var i=0;i<str.length;i++){
        if(isNaN(str.charAt(i))!=true){//非数字返回true
            if(str.charAt(i)!=0){
                ++t;
            }
        }
    }
    return t;
}
str2="C3an you1 can a ca6n as a Can4ner can c3an a can";
writeDocument("'"+str2+"'"+"中一共有"+sz(str2)+"个数字");