13 JavaScript Array对象&Boolean对象&Math对象

Posted 2021-05-07  Island

万物皆对象，数组是对象，数组可以存储元素，函数，数组等对象

创建数组的三个方式：

• 常规方式：var myCars = new Array();
• 简介方式：var myCars = new Arrray("Benz","BMW",“Audi”);
• 字面：var Array = ["Benz","BMW","Audi"];

<script>
var i;
var myCars = new Array();
var myCars1 = new Array("a","b","c");
var myCars2 = new Array("z","y","w");
myCars[0] = "Benz";
myCars[1] = "BMW";
myCars[2] = "Audi";
for(i = 0; i < myCars.length; i ++){
    document.write(myCars[i]+"<br/>"+myCars1[i]+"<br/>"+myCars2[i]+"<br/>");
}
</script>

 

Boolean对象：

如果布尔对象的初始值为以下，则它是false:

• 0
• -0
• null
• ""
• false
• undefined
• NaN

 

Math对象：

• 用于执行数学任务，比如求平方根sqrt(),比如π,pi