{"id":1362,"date":"2024-06-02T22:24:06","date_gmt":"2024-06-02T22:24:06","guid":{"rendered":""},"modified":"2024-06-05T03:09:46","modified_gmt":"2024-06-04T19:09:46","slug":"es6-%e7%b3%bb%e5%88%97%e4%b9%8b-let-%e5%92%8c-const","status":"publish","type":"post","link":"https:\/\/www.lccc.top\/?p=1362","title":{"rendered":"ES6 \u7cfb\u5217\u4e4b let \u548c const"},"content":{"rendered":"\n

\u5757\u7ea7\u4f5c\u7528\u57df\u7684\u51fa\u73b0<\/h2>\n

\u901a\u8fc7 var \u58f0\u660e\u7684\u53d8\u91cf\u5b58\u5728\u53d8\u91cf\u63d0\u5347\u7684\u7279\u6027\uff1a<\/p>\n

<\/p>\n
if<\/span> (<\/span>condition<\/span>)<\/span> {<\/span>\n    var<\/span> value<\/span> =<\/span> 1<\/span>;<\/span>\n}<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>value<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u521d\u5b66\u8005\u53ef\u80fd\u4f1a\u89c9\u5f97\u53ea\u6709 condition \u4e3a true \u7684\u65f6\u5019\uff0c\u624d\u4f1a\u521b\u5efa value\uff0c\u5982\u679c condition \u4e3a false\uff0c\u7ed3\u679c\u5e94\u8be5\u662f\u62a5\u9519\uff0c\u7136\u800c\u56e0\u4e3a\u53d8\u91cf\u63d0\u5347\u7684\u539f\u56e0\uff0c\u4ee3\u7801\u76f8\u5f53\u4e8e\uff1a<\/p>\n
<\/p>\n
var<\/span> value<\/span>;<\/span>\nif<\/span> (<\/span>condition<\/span>)<\/span> {<\/span>\n    value<\/span> =<\/span> 1<\/span>;<\/span>\n}<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>value<\/span>)<\/span>;<\/span><\/pre>\n<\/div>\n
\u5982\u679c condition \u4e3a false\uff0c\u7ed3\u679c\u4f1a\u662f undefined\u3002<\/p>\n
\u9664\u6b64\u4e4b\u5916\uff0c\u5728 for \u5faa\u73af\u4e2d\uff1a<\/p>\n
<\/p>\n
for<\/span> (<\/span>var<\/span> i<\/span> =<\/span> 0<\/span>;<\/span> i<\/span> <<\/span> 10<\/span>;<\/span> i<\/span>++<\/span>)<\/span> {<\/span>\n    ...\n}<\/span>\nconsole<\/span>.<\/span>log<\/span>(<\/span>i<\/span>)<\/span>;<\/span> \/\/ 10<\/span><\/pre>\n<\/div>\n
\u5373\u4fbf\u5faa\u73af\u5df2\u7ecf\u7ed3\u675f\u4e86\uff0c\u6211\u4eec\u4f9d\u7136\u53ef\u4ee5\u8bbf\u95ee i \u7684\u503c\u3002<\/p>\n
\u4e3a\u4e86\u52a0\u5f3a\u5bf9\u53d8\u91cf\u751f\u547d\u5468\u671f\u7684\u63a7\u5236\uff0cECMAScript 6 \u5f15\u5165\u4e86\u5757\u7ea7\u4f5c\u7528\u57df\u3002<\/p>\n
\u5757\u7ea7\u4f5c\u7528\u57df\u5b58\u5728\u4e8e\uff1a<\/p>\n