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测试您的JavaScript知识

单选题

下面这行会返回什么值？ "" ? "a" : "b"

• ""
• a
• b
• undefined

单选题

The length property of an Array object is always:

• Equal to the number of properties in that object
• Equal to the highest index of that object +1
• Equal to the highest index of that object

单选题

执行这句之后 var x = 1 == '1';
x的值为

• 1
• '1'
• false
• true
• undefined

单选题

执行这句之后 var x = 1 === '1';
x的值为

• 1
• '1'
• false
• true
• undefined

单选题

var str = "what is this"; var x = str.search("is");
What is the value of x?

• 1
• 2
• 3
• 4
• 5
• 6
• 7

单选题

Which of the following is not a method in the "JSON" object according to the ECMAScript specification?

• JSON.fromString
• JSON.stringify
• JSON.parse

单选题

Which is not a primitive data type in JavaScript?

• string
• character
• number
• boolean

单选题

var myVar = '5'; var myAddedVar = myVar + 10;
myAddedVar的值为：

• NaN
• 510
• '510'
• 程序将出错
• 15

单选题

var x = ['foo', 'bar']; x.length = 1;
x的值为：

• ['foo', 'bar']
• ['foo', 'bar', 1]
• ['foo']
• ['bar']
• []

单选题

var x = "hello"; (function() { x = "goodbye"; }());
x的值为：

• "hello"
• "goodbye"
• undefined 并抛出语法错误

单选题

var data = [1, 2, 3, 4, 5, 6]; data.shift();
data的值为：

• [1, 2, 3, 4, 5]
• [2, 3, 4, 5, 6]
• [undefined, 1, 2, 3, 4, 5]
• [6, 1, 2, 3, 4, 5]
• [undefined, 2, 3, 4, 5, 6]

单选题

var _ = '_'; x = parseInt(_);
x的值为：

• NaN
• '/e242'
• 242
• Syntax Error: unexpected identifier
• Type Error: incorrect type of argument, expect Number but was String

单选题

var x = typeof null;
x的值为：

• "undefined"
• "object"
• "null"
• "array"
• "string"

单选题

var x = typeof null123;
x的值为：

• "undefined"
• "object"
• "null"
• "array"
• "string"

单选题

var x = 1 + 5 + " bottles of milk";
x的值为：

• "15 bottles of milk"
• "6 bottles of milk"
• "5 bottles of milk"
• NaN
• Undefined

单选题

var x = (NaN === NaN) ? true : false;
x的值为：

• true
• false
• 语法错误

单选题

function foo(y) { var z = 10; z = 7; }; var x = foo("bar");
x的值为：

• 7
• null
• undefined
• 10
• "bar"

总结

您的得分: 平均分: 8 最高分: 11