javascript&jquery类型 [1]¶

字符串¶

类型:
```
typeof "some string";  // "string"
```

内置方法:

"hello".charAt( 0 ) // "h"
"hello".toUpperCase() // "HELLO"
"Hello".toLowerCase() // "hello"
"hello".replace( /e|o/g, "x" ) // "hxllx"
"1,2,3".split(",") // [ "1", "2", "3" ]

"Hello".length // 5

数字类型¶

类型:

typeof 12 // "number"
typeof 3.543 // "number"

说明:

0.1 + 0.2 // 0.30000000000000004

Math.PI // 3.141592653589793
Math.cos( Math.PI ) // -1

parseInt( "123" ) = 123 // (implicit decimal)
parseInt( "010" ) = 8 // (implicit octal)
parseInt( "0xCAFE" ) = 51966 // (implicit hexadecimal)
parseInt( "010", 10 ) = 10 // (explicit decimal)
parseInt( "11", 2 ) = 3 // (explicit binary)
parseFloat( "10.10" ) = 10.1

"" + 1 + 2; // "12"
"" + ( 1 + 2 ); // "3"
"" + 0.0000001; // "1e-7"
parseInt( 0.0000001 ); // 1 (!)

String( 1 ) + String( 2 ); // "12"
String( 1 + 2 ); // "3"

parseInt( "hello", 10 ) // NaN
isNaN( parseInt("hello", 10) ) // true

1 / 0 // Infinity

typeof NaN // "number"
typeof Infinity // "number"

NaN == NaN // false (!)

Infinity == Infinity // true

object对象¶

类型:

var x = {};
var y = {
  name: "Pete",
  age: 15
};

typeof {} // "object"

实例:

// Dot Notation
y.name // "Pete"
y.age // 15
x.name = y.name + " Pan" // "Pete Pan"
x.age = y.age + 1 // 16

// Array Notation
var operations = {
  increase: "++",
  decrease: "--"
};
var operation = "increase";
operations[ operation ] // "++"
operations[ "multiply" ] = "*"; // "*"

// Iteration
var obj = {
  name: "Pete",
  age: 15
};
for( key in obj ) {
  alert( "key is " + [ key ] + ", value is " + obj[ key ] );
}

// jquery自带foreach方法
jQuery.each( obj, function( key, value ) {
  console.log( "key", key, "value", value );
});

// Prototype
??暂不解

Array数组¶

类型:

var x = [];
var y = [ 1, 2, 3 ];

typeof []; // "object"
typeof [ 1, 2, 3 ]; // "object"

实例:

for ( var i = 0, j = a.length; i < j; i++ ) {
  // Do something with a[i]. PS:这方法只需要计算一次a.length
}

var x = [ 'a', 'b', 'c' ];
jQuery.each( x, function( index, value ) {
  console.log( "index", index, "value", value );
});

var x = [];
x.push( 1 );
x[ x.length ] = 2;
x // [ 1, 2 ]

var x = [ 0, 3, 1, 2 ];
x.reverse()      // [ 2, 1, 3, 0 ]
x.join(" – ")    // "2 - 1 - 3 - 0"
x.pop()          //
x.unshift( -1 )  // 可向数组的开头添加一个或更多元素，并返回新的长度
x.shift()        // 方法用于把数组的第一个元素从其中删除，并返回第一个元素的值
x.sort()         //
x.splice( 1, 2, 3, 4，5) // [ 2, 3 ]从下标1开始删除之后2个数，然后增加3,4,5三个数

PlainObject扁平对象¶

PlainObject类型主要被ajax函数用于保存数据請求。这种类型可能是 string 或 array<form elements>:

{ 'key[]': [ 'valuea', 'valueb' ] }

on server-side:

<?php
$_REQUEST['key'][0]="valuea";
$_REQUEST['key'][1]="valueb";

Function函数¶

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