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20220330_Vote/Ewide.Web.Entry/wwwroot/lib/xe-utils/padStart.js

@@ -0,0 +1,32 @@
+var toValueString = require('./toValueString')
+
+var isUndefined = require('./isUndefined')
+
+var helperStringRepeat = require('./helperStringRepeat')
+
+/**
+  * 用指定字符从前面开始补全字符串
+  *
+  * @param {String} str 字符串
+  * @param {Number} targetLength 结果长度
+  * @param {Number} padString 补全字符
+  * @return {String}
+  */
+function padStart (str, targetLength, padString) {
+  var rest = toValueString(str)
+  targetLength = targetLength >> 0
+  padString = isUndefined(padString) ? ' ' : '' + padString
+  if (rest.padStart) {
+    return rest.padStart(targetLength, padString)
+  }
+  if (targetLength > rest.length) {
+    targetLength -= rest.length
+    if (targetLength > padString.length) {
+      padString += helperStringRepeat(padString, targetLength / padString.length)
+    }
+    return padString.slice(0, targetLength) + rest
+  }
+  return rest
+}
+
+module.exports = padStart