Update JavaScript_基础.md

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@ -54,7 +54,7 @@ lang = lang + "Script";
```javascript
var a = null;
a.toString() // Uncaught TypeError: Cannot read property 'toString' of null
String(a) // "null"
String(a) // "null"
```
**3. 常用的字符串操作**
@ -87,12 +87,12 @@ alert(stringValue.substr(3, 7)); // "lo worl"
// 当第一个参数为负值时
alert(stringValue.slice(-3)); // "rld" 按照规则等价于: slice(8)
alert(stringValue.substring(-3)); // "hello world" 按照规则等价于: substring(0)
alert(stringValue.substring(-3)); // "hello world" 按照规则等价于: substring(0)
alert(stringValue.substr(-3)); // "rld" 按照规则等价于: substr(8)
// 当第二个参数为负值时
alert(stringValue.slice(3, -4)); // "lo w" 按照规则等价于: slice(3,7)
alert(stringValue.substring(3, -4)); // "hel" 按照规则等价于: substring(3,0)
alert(stringValue.substring(3, -4)); // "hel" 按照规则等价于: substring(3,0)
alert(stringValue.substr(3, -4)); // ""(空字符串) 按照规则等价于: substr(3,0)
```
@ -236,9 +236,9 @@ var colors = ["red", "blue", "green"];
```javascript
var colors = ["red", "blue", "green"];
colors.length = 2; // ["red", "blue"]
colors[colors.length] = "green"; // ["red", "blue", "green"]
colors[10] = "black"; // ["red", "blue", "green", empty × 7, "black"]
colors.length = 2; // ["red", "blue"]
colors[colors.length] = "green"; // ["red", "blue", "green"]
colors[10] = "black"; // ["red", "blue", "green", empty × 7, "black"]
```
数组的其他常用方法如下:
@ -279,8 +279,8 @@ CMAScript 的数组提供了类似栈的特性,能够实现先进先出:
```javascript
colors.push("black","yellow"); // ["red", "blue", "green", "black", "yellow"]
colors.shift() // "red"
colors // ["blue", "green", "black", "yellow"]
colors.shift() // "red"
colors // ["blue", "green", "black", "yellow"]
```
**5. 重排序方法**
@ -346,8 +346,8 @@ var colors = ["red", "green", "blue", "yellow", "green", "blue"];
colors.indexOf("green"); // 1
colors.indexOf("green", 3); // 4
colors.lastIndexOf("green"); // 4
colors.lastIndexOf("green", 3); // 1
colors.lastIndexOf("green"); // 4
colors.lastIndexOf("green", 3); // 1
```
**8. 迭代方法**