17 lines
458 B
JavaScript
17 lines
458 B
JavaScript
var toValueString = require('./toValueString')
|
|
|
|
/**
|
|
* 判断字符串是否在源字符串的头部
|
|
*
|
|
* @param {String} str 字符串
|
|
* @param {String/Number} val 值
|
|
* @param {Number} startIndex 开始索引
|
|
* @return {String}
|
|
*/
|
|
function startsWith (str, val, startIndex) {
|
|
var rest = toValueString(str)
|
|
return (arguments.length === 1 ? rest : rest.substring(startIndex)).indexOf(val) === 0
|
|
}
|
|
|
|
module.exports = startsWith
|