2.13-ES6字符串

模板字符串

模版字符串

1、反單引號引起來

2 、遇到變量用${}括起來

3 、原理 正則實現

        let name = 'along';
        let age = 32;
        let res = `My name is ${name},I am ${age} years old`;
        console.log(res);

模板字符串拼接

  let info = [name,age];
        let lis = info.map(function(item) {
            return `<li>${item}</li>`;
        });
        let ulString = `
            <ul>
                ${lis.join('')}
            </ul>
        `;
        document.write(ulString);  //將拼接的字符串寫到頁面

模板標籤

		//定義tag標籤
		function tag(str) {
            console.log(str); 
            console.log(arguments);// {0:['My name is ',',I am ',' years old'],1:'along',2:32} 
            let res = ''; 
            let arr = [];
            let arr2 = arguments[0];
            for(var k in arguments) {
                if(k !=0) {
                    arr.push(arguments[k]);
                }
            }
            for(var key in arr) {
                res += arr2[key].toUpperCase() + arr[key].toString().toUpperCase();
            }
            res += arr2[arr2.length-1].toUpperCase();
            console.log(res);   
        }
        // 模版標籤，tag標籤，需要定義
        let res2 = tag`My name is ${name},I am ${age} years old`;

字符串操作

startsWith() 以某字串開頭

endWith() 以某字串結尾

includes() 是否包含某字串

repeat() 重複

padStart()/padEnd() 填充首部填充/尾部填充

		let url = 'http://www.baidu.com';
        let flag = url.startsWith('Http'); // false
        console.log(flag);
        // endWith()
        let img_name = '2.png';
        let bool = img_name.endsWith('png'); 
        console.log(bool); // true
        // includes() 是否包含某字串
        console.log('along666'.includes('L'));
        // repeat()
      
console.log('abc'.repeat(3));
        // padStart()/padEnd()
        console.log('0'.padStart(8,9)); // 8總長度 9填充字符 '77777770'
        console.log('0'.padEnd(8,9)); // 09999999