lovecoding
/
VIP22


			
				
					
						
						
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  <title>Document</title>
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  <script>
    /* length属性 返回字符串的长度
    var text = 'asdasdasdasdasdasdasd'
    var a = text.length
    console.log(a) */

    /* indexOf()方法 返回字符串中指定文本首次出现的索引位置
    var str = "my name is xiaoming,I'm from china, is "
    var a = str.indexOf('china')
    console.log(a) */

    /* lastIndexOf()方法  返回指定文本最后一次出现的索引
    var str = "my name is xiaoming,I'm from china, is "
    var a = str.lastIndexOf('is')
    console.log(a) */

    /* var str = "my name is xiaoming,I'm from china, is xiaoming"
    var a = str.search('xiaoming')
    console.log(a) */

    /* var str = "my name is xiaoming,I'm from china, is xiaoming"
    var a = str.indexOf('xiaoming',20)
    console.log(a) */

    /* slice()方法 提取字符串中某个部分  新的字符串中返回被提取的部分
    var str = 'apple, banana, orange'
    var a = str.slice(7,13)
    console.log(a)
    console.log(str) */

    /* 参数为负数的时候  从字符串结尾开始倒数
    var str = 'apple, banana, orange'
    var a = str.slice(-13,-7)
    console.log(a) */

    /* substring() 方法 类似于slice()
    但是  substring()不能接收负的索引
    var str = 'apple, banana, orange'
    var a = str.substring(7,13)
    console.log(a) */

    /* substr() 第一个参数 为起始索引
    第二个参数 为裁剪的长度
    var str = 'apple, banana, orange'
    var a = str.substr(7,6)
    console.log(a) */

    /* replace()方法用于另一个值替换在字符串中指定的值
    默认的  replace()只替换首个匹配
    var str = 'please sit down'
    var a = str.replace('please','Please')
    console.log(a) */

    /* toUpperCase() 把字符串转化为大写
    var str = 'hello word'
    var a = str.toUpperCase()
    console.log(a) */

    /* toLowerCase()把字符串转化为小写
    var str = 'HELLO WORD'
    var a = str.toLowerCase()
    console.log(a) */

    /* concat()用于连接
    var a = 'hello'
    var b = 'word'
    c = a.concat(" ",b)
    console.log(c) */

    /* trim()方法 删除字符串两端的空白符
    var str = '                  hello     word!                ';
    alert(str.trim()) */

    /* charAt()返回字符串中指定位置的字符串
    var str = 'HELLO WORD'
    var a = str.charAt(0)
    console.log(a) */

    /* split()方法 可以将字符串转为数组
    var text = 'a,b,c,d,e,f'
    console.log(text.split(",")) */
  </script>
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