Javascript学习笔记----DataType and Values

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