Code var str ="Zhuobin"; var last_char = str.charAt(str.length-1);//----n var sub = str.substring(0,4);//--zhuo var i = str.indexOf('Z');//--0 2.Converting number to string Number are automatically to string when need. number + string = string number +""= string var _string = String(number); Another way: var _string = number.toString(); var n =17; 2_string = n.toString(2);//--10001 8_string = n.toString(8);//--021 16_string = n.toString(16);//--0x11 // var n =123456.789\ n.toFixed(0);//123457 n.toFixed(2);//--123456.79 n.toExponential(1);//1.2e+5 n.toExponential(3);//1.23//指数表示 n.toPrecision(4);//1.235e+5//四舍五入 n.toPrecision(7);//123456.8