<script>

    //trim();去除前后的空格

    var str = "     你好  我很好！     ";

    console.log(str);

    console.log(str.trim());

    console.log("--------------------");

    //replace(); 替换和全局替换值。

    var str = "Today is fine day,today is fine day!"

    console.log(str);

    console.log(str.replace(/today/ig, "tomorrow"));//i忽略大小写，g代表全局

    console.log("--------------------");

    //search();  给字符差索引

    var str = "abcdefg";

    console.log(str.search(/bc/));

    console.log(str.indexOf("bc"));

</script>

<script>

    var str = "     你好，我      很好！      ";

    console.log(str);

    console.log(trim(str));

    function trim(str) {

        var aaa = str.replace(/(^\s+)|(\s+$)/g, "");

        return aaa;

    }

</script>